Eugene, an avid self-taught DIYer and engineer, has acquired almost 40 years of experience with power/hand tools, plumbing, and woodwork.
An Overflowing Water Tank in Your Attic
You hear water running outside your home. You look up and see a pipe sticking out from the edge of the roof or soffit which you've never even noticed before. Water is trickling out from the pipe and down onto the ground.
That mysterious pipe is the overflow from the cold water header tank (also called a cistern) in your attic. If the tank overfills, excess water flows safely via the overflow to the outdoors. It's not likely to be a catastrophe, and the flow may only be a trickle, but if you have a water meter and pay for your water, obviously the cost of this wastage can add up.
What's Covered in This Guide
This guide explains the basics of the pipes and valves in home plumbing systems and how to remedy an overflowing cold-water tank in the loft. This tank is commonly found in UK plumbing systems. You can use the same repair principles for remedying a leaking toilet cistern. There is some variation in the type of valves fitted to tanks. Newer tanks are fitted with diaphragm valves, whereas older tanks use a sliding valve system with a replaceable washer as shown in the photos below.
Note: This article covers replacing a washer in an old style ballcock valve (part 1 valve). This valve is actually against regulations in new installations. There are several different types of valves different to the one below, but all of them use some form of fiber/rubber washer/O-ring/diaphragm system to shut off flow.
What Is the Cold Water Tank in the Attic For?
The cold tank in the loft serves three purposes:
- It collects expanding water as it rises in the expansion tube when the water in the hot tank is heated or overheats. This is the case with a vented hot tank. The alternative system is a sealed hot tank with an expansion vessel to accommodate water as it expands when heated.
- The second function of the tank is to provide a pressure head and feed for the hot water tank (gravity feed). Water flows out from the bottom of the cold tank (the blue line in the diagram below) to the bottom of the hot tank. Because the cold tank is higher than the hot tank, the resulting pressure forces water through the tank and out the top. Water in the hot tank is heated by an electric (immersion) element and/or heating system boiler (furnace). Modern hot water systems may use a pump to provide the pressure.
- It acts as a storage reservoir and can supply water in the event of an interruption in supply from your water company. This cold water supplies WCs, showers, baths and hand basin taps (faucets). The water isn't drinkable and shouldn't supply the cold taps in the kitchen because it has been lying indefinitely in an open tank into which anything could have dropped (insects, spiders, and possibly birds, bats and their droppings!).
Older buildings only use the tank in the attic for pressurizing the hot water tank and water is fed from the rising main to all fixtures. This is called a "direct system". In some countries, the tank isn't common and pressure for the hot water supply is derived from a pump.
Indirect and Direct Plumbing Systems
- Indirect Plumbing system. The cistern/tank in the loft and also the cold tap in the kitchen is fed by the rising main. All other cold taps and water fittings get their supply from it. The cistern also creates the pressure for the hot water tank
- Direct plumbing system. All cold taps are fed from the rising main. This is less complicated, but the high water pressure can cause noise and water hammer in taps.
Domestic Plumbing Systems: Pipe Layout in House (Indirect Plumbing System)
The diagram below outlines the most basic plumbing arrangement in a house. This is an indirect plumbing system which is found in most homes.You may have extra plumbing fixtures, but the basic principle is the same, although the hot water tank can be located on the ground floor or on upper floors. Some older houses may not have a tank in the loft.
Inside your home, several gate or ball valves allow water to be shut off to various sections of the plumbing system. A gate valve has a wheel/knob which is turned clockwise to shut off flow. A ball or quadrant valve has a lever handle which is lined up with the pipe when the valve is on. To turn it off, the handle must be turned through 90 degrees so that it is perpendicular to the pipe. There may also be small, inline isolating valves for disconnecting water to each appliance. These are operated with a slotted head screwdriver.
Indirect Plumbing System
How Valves Are Used to Isolate Sections of the Plumbing
Water enters the building at ground level. Referring to the diagram above:
- Valve 1 is located directly outside the premises on a wall or in a box in the ground. This normally has a square section on the end of the shaft and needs to be operated with a key. In colder climates, it may be in the basement. This enables the water supply entering the building to be cut off. Unlike a gate valve, this valve has a rubber seal which tightens against a seat so that water can be totally shut off. There may be another stopcock outside the boundary of the premises under an inspection cover but sometimes this is shared and cuts off water to several homes
- Valve 2 located indoors is the main stop cock, and shuts off water where the service main enters the building. Drinking water must not be supplied from the tank in the loft, and comes directly from the service main.
- Valve 3 shuts off the feed to the cold water tank in the loft to allow maintenance or drainage of the tank.
- Valve 4 shuts off the cold feed to the bottom of the hot tank, removing the pressure, and this prevents hot water leaving the top of the tank.
- Valve 5 shuts off feed to WCs, baths, showers, wash basins etc. There may only be one feed pipe from the cold tank to both the hot water tank and these fixtures, in which case there will only be one valve to shut off this supply, i.e one valve shuts off both cold water and hot water (because pressure is removed).
You may have additional valves feeding each appliance. These valves are usually small isolating types which are operated by turning a screw or short lever.
The hot tank is vented to the atmosphere via an expansion pipe which runs up into the loft to the cold tank. This allows expansion to take place without restriction as water is heated. Also if the heating system malfunctions and water in the tank boils, steam can escape and water can flow safely back into the cold tank.
Three Different Types of Valves For Shutting Off Water
These are the three types of valves you're likely to find in your home for shutting off water.
What Is the Small Tank in the Loft for?
If you have an open or vented heating system, there will also be a small reservoir tank in your attic. This is a feed and expansion (F&E) tank and continuously tops up water in the heating system as well as collecting any water that expands upwards as it heats up. An expansion pipe runs from the boiler up to the tank and then bends downwards over the tank so that water can drain. If your central heating system overheats, this pipe can also vent steam. Overheating could be caused by faulty thermostats forcing an oil or gas boiler to remain on all the time, but more likely due to a circulating pump failure (or loss of power to the pump) on a solid fuel system with a back boiler and the radiators upstairs turned off.
The tank is normally fed by the same cold water pipe as the larger tank. This small tank also has a ball cock which can suffer from the same problems as the main cold water tank.
How Does a Ballcock Valve Work?
The tank in the loft is fitted with a ballcock valve (also known as a balltap or float valve) to prevent it over filling. This is the same as the system used in a toilet cistern. Water enters via the valve, and as the level in the tank rises, it pushes upwards on the underside of a plastic or brass float attached to a lever arm. The leverage of the arm creates sufficient force to close the valve once the tank has sufficiently filled.
What Causes the Cold Tank to Overflow?
- The float has developed a leak so that it fills with water, sinking, or providing insufficient force to close the valve
- The rubber washer in the valve has deteriorated so that it doesn't seal properly
- The brass nipple in the valve has worn to such an extent from decades of abrasion by particles in the water that it won't seal anymore. (a ridge can develop in the wall of the nipple's tip. In this case, the valve will have to be replaced
Any of these scenarios will cause the water level to rise in the tank, eventually causing an overflow.
What Tools are Needed to Replace a Washer in the Ballcock Valve?
- Water pump pliers or alternatively a pipe wrench (Stilson wrench) or vise grips
- Flat blade screwdriver
- Small pliers
- Long-nose (snipe-nose) pliers (not essential, but useful for pulling out the split pin)
- Torch (ideally a head torch)
These are just some of the 20 Essential Tools You Need For Home Maintenance
Step 1: Turn Off the Valve on the Pipe Feeding the Tank
As described in the explanation of plumbing systems above, this is valve 3. This may be located downstairs, near the cold tank or near the hot tank. You will have to trace the piping and by a process of elimination, identify which valve controls what. If you push the float of the ball cock downwards and no water flows into the tank, you have found the right valve. Usually valve 3 (shown in the diagram above) feeding the tank is on a 1/2 inch / 15 mm pipe.
Step 2: Remove the End Cap From the Valve in the Tank
The valve on this tank is a slider type. Inside the body of the valve is a nylon or brass slider with a rubber washer embedded in the end. Water flows out through a nipple inside the valve. The slider is pushed against this nipple by the float arm and this cuts off flow.
Using the water pump pliers, pipe wrench or vise grips, unscrew the end cap. If it's obstinate and refuses to turn, try pouring some hot water from a kettle over the cap, this should expand it slightly and make it easier to turn.
Step 3: Remove the Split Pin
A split (cotter) pin holds the float arm in place. Squeeze the two ends together with the pliers. Now use the long nose pliers to grip the looped end of the pin and pull it out. If you rotate the pin backwards and forwards while pulling, it makes it easier. If it's really tight, tap it with a hammer (don't hit it hard, just use lots of light taps).
Step 4: Remove the Float Arm
There is a knack to doing this. Move the float arm into a horizontal position and then pull it downwards. You will likely need to wiggle it a bit to get it out.
Step 5: Check the Float
Over time, floats can become cracked or develop leaks where they screw onto the arm. Shake the float to see whether there's any water in it. You can buy replacement floats in a hardware store.
Step 6: Remove the Slider
Push a narrow blade screwdriver up into the slot in the underside of the valve. Push the slider so that it sticks out of the valve body. You won't get it all the way out with the screwdriver, so grip the end and pull it out with your fingers or nails.
If the washer looks ok and isn't excessively worn, the nipple in the valve might be worn so that it doesn't seal properly against the washer. If this is the case, consider replacing the complete valve. A new valve will have a push type fitting suitable for connecting to copper or plastic tubing, or alternatively a compression fitting. You can read more about these type of fittings in A Complete Guide to Using Plumbing Fittings for Joining PVC, PEX, and Copper Pipe.
Step 7: Remove the Washer
Sliders are of two types: Older types are solid brass with a screwed on end cap or groove that holds the washer in place or nylon like the one in the photo below with the washer just pushed into a space in the end. If your ballcock has a nylon slider, simply push the washer out with a screwdriver and clean out any remaining fragments of rubber.
Step 8: Replace the Washer
You can buy a washer in a store or make one from a suitably thick scrap of sheet rubber. If you are making one, use the perimeter of the slider as a guide and then pare to fit. Push the washer back into the slot of the slider, using the screwdriver to stop the rubber catching in the edges of the slot. Once you get it in halfway, lay the valve on its side and push it in fully with your thumbs.
Step 9: Replace the Slider, Float Arm and End Cap
Push the slider back into the valve body ensuring that the slot in the slider is aligned with the slot in the underside of the valve body. You can use the screwdriver to feel whether it is lined up. Replacing the float arm can be tricky if the two slots don't line up. Hold the arm horizontally and push upwards, wiggling it a bit helps to get it into place. Push the split pin back into place and splay the two ends slightly apart with a screwdriver. They don't need to be spread far apart. Replace the end cap and screw tight, hand tight is good enough. A smear of Vaseline on the threads helps to prevent seizing should it be necessary to remove the cap in the future. You can do this on threads of taps also when re-assembling.
Step 10: Turn the Water Back On
Turn the water back on. Hold the underside of the lever arm, and pull it upwards to validate that the valve cuts off water properly. Initially water will gush into the tank and the level will rise quickly. However as the tank fills, the valve will start to close and flow will dwindle, so it can take ages for water to stop dripping because of the slow rise of water level. Don't worry if this is the case.
Recommended DIY Books Covering Plumbing
I learned a huge amount of information from this book! The Collins Complete DIY Manual is an excellent guide, comprehensively covering plumbing, electrics, woodwork, heating, garden construction, paving, plasterwork, glass cutting, painting, tiling and all other aspects of home maintenance and improvement. This older version from Amazon UK (several available second hand, with "good" to "very good" ratings) contains a lot more info than the newer editions.
Note that electrics info in this manual is geared towards UK users.
Adjusting Ballcock to Change Water Level
In a toilet cistern, you can conserve water by placing a plastic bottle filled with water into the tank. This reduces the amount of water used every time you flush. Alternatively, you can use a piece of brick or other heavy object. Another option is to adjust the ballcock arm so that it shuts off the water valve when the water level is lower.
If there is no screw which facilitates making an adjustment and the arm is the older-style brass type, hold the arm securely in the middle so as not to damage the valve. With your other hand, grasp the arm just before the ball float. Bend the arm downwards so that it ends up being curved downwards. Water will now force the float to act on the arm and close the valve at a lower level. Newer style ballcock valves have a screw for adjusting level. Turn the screw clockwise to reduce the level to which the tank fills.
How to Stop a Cold Tank From Freezing in Winter
Modern lofts have their floor insulated so not a lot of heat permeates up into the loft space, especially if upstairs radiators are turned off. The result is that the cold water tank can start to freeze. If you're regularly running taps and using the shower, the main cold tank continually fills with new water, so this is less likely to happen, but pipes in the attic can freeze and burst if a home is vacant for a couple of days during extended snowy and cold periods. This is especially the case if plumbing is copper, and pipes can freeze in very cold weather even if they're lagged. PEX plumbing because it's flexible, is better at tolerating sub-zero temperatures because the plastic has more "give" and can stretch.
The smaller water tank used for topping up the central heating system and collecting water as it heats up and expands (or the system overheats and water boils) is much more likely to freeze because water isn't continually replaced. So in cold weather, it's a good idea to leave the trapdoor to your attic open and allow some heat up into the space to prevent this happening.
Be Prepared! Plumbing Tip
The Boy Scout motto is "Be Prepared!" so take a leaf out of their book by locating and identifying all the valves in your home! Work out what they do and write the function on the wall behind with a thick marker. Alternatively, tie a label around the stem of the valve. Gate valves can seize up after years of disuse so every so often (once a year), give them some exercise by turning on and back off again. If a pipe springs a leak in your home, you don't want to be running around figuring out how to turn off the water.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: Why is the overflow still dripping after replacing the ballcock?
Answer: Presumably this is because water is rising too high and reaching the level of the overflow outlet. If the overflow pipe still drips after replacing the ballcock, check first that the ball on the end of the lever can move unrestricted in the tank and there isn't anything obstructing it. If you didn't replace the ball float, this could be punctured, slowly letting in water and partially full. The result is that water would need to rise higher to create sufficient force to close the valve. Another possibility is that adjustment is necessary because the new ballcock has a different length arm. If it has an adjustment screw, turn this anti-clockwise or clockwise so that the valve shuts off when the water has reached a lower level.
Question: I've replaced completely the 3/4" ballcock on my loft water storage tank serving my power shower. However the I'm having difficulty aligning the threaded female elbow connection to the existing pipework. How do I achieve a watertight seal when the elbow isn't fully tightening on the ballcock inlet? I have fully tightened the elbow is 90 degrees out of the previous position.
Answer: I'm not a plumber, so I don't know whether this is the recommended solution, but I had a similar problem attaching an elbow to the ballcock in a toilet cistern. I simply use more PTFE sealing tape so that the fitting starts to tighten up a couple of threads before the male part reaches the "end of the line" on the threads in the female elbow. If you discover that you've gone too far, and the fitting can't be tightened further around to the correctly aligned position, don't loosen it, to re-align as it may leak. Undo and re-apply tape again. It might be helpful to post on plumbing forums to get a second opinion.
Question: Why does the overflow from my header tank drip during the night but not during the day?
Answer: During the day, you're using water regularly, so the water level never reaches the overflow outlet. At night the water level may be slowly rising due to a trickle of water flowing into the tank from a faulty ballcock valve, so it has plenty of time to reach the overflow.
Question: I have two header tanks up in my loft, one big tank and another small tank with a similar configuration. Why is tank number two overflowing to the roof?
Answer: The smaller tank is likely to be the expansion tank for the central heating system. Just like the main cold water tank, this will overflow if the ballcock washer is worn or if it is set up so that water level reaches the overflow before the float shuts off the valve.
Question: We had this done three weeks ago (at great expense). There is now a quite loud and droning noise when we turn the shower on or run water for a while. The plumber has come around but of course it did not happen while he was here. Do you know why this might be happening? The plumber said it might happen for a day or two but three weeks seems a bit much. It is annoying but is it a signal of something more sinister?
Answer: The noise is presumably due to the tank filling when it drains when hot or cold water runs. The sound could be due to water hitting the existing water in the tank as it fills; vibration in pipes as water turns on and off (water hammer) or sound from the valve itself as water exits. Sometimes pipes can bang against each other so clipping them properly so they can't move may help (or sliding small sections of insulation onto them to separate them).
Replacing a section of copper tubing where it enters the tank with about a meter of PEX tubing may also help. PEX tends to give more of a cushioning effect than copper.
The jet in the valve or the valve itself may be a low-pressure type that's primarily used for filling tanks rapidly (e.g., agricultural water troughs). It may be possible to replace the jet in the valve (or maybe the whole valve would have to be replaced) with a high-pressure type that fills the tank more slowly.
Have a look at these links that discuss the problem in a little more detail:
Question: I have no cold water coming from the taps in my bathroom and the toilet cistern isn't filling. What's wrong?
Answer: If you have an indirect plumbing system, cold water that fills the toilet cistern (and possibly also bathroom taps) comes from the tank in the attic. Look for a quadrant valve (ball valve) in the water line that feeds these appliances. Sometimes this is located in the hot press near your hot water tank. These valves have a lever that should be in line with the water pipe when turned on, and perpendicular to the pipe when turned off. It is possible to inadvertently knock off the valve if you lean on it by accident. Before you do this, however, you need to confirm that it is not a gas valve which has been turned off for some reason.
Another scenario for having no water is that the ballcock in the cold water tank in the loft has stuck and the tank has emptied.
Question: I have no hot water. What could be the problem?
Answer: If you have a cold water tank in the loft, this produces the pressure to force water out of the hot tank. A valve, sometimes located in the hot press, turns on the cold water feed to the bottom of the hot tank which forces hot water out the top. This may be a quadrant valve which has a lever. The lever should be parallel to the pipe and perpendicular to the pipe when off. It is possible for the valve to be inadvertently knocked off, so just turn it back on. Before you do this, however, you need to confirm that it is not a gas valve which has been turned off for some reason.
Question: Warm water is coming into the header tank at the bottom, is this normal? I'm wondering if this could be the reason the overflow is still dripping?
Answer: Sounds odd. The header tank pressurizes the hot tank by feeding it from the bottom. If the water in the hot tank becomes excessively hot due to a failed immersion thermostat causing the element to run continuously, water could boil in the tank and eventually some of it could be expelled through the expansion pipe into the tank. The same would happen if the tank is heated by a back boiler and the circulation pump fails, or radiators are turned off upstairs, causing the tank to overheat. I've noticed in my own house that warm water in the small header tank that tops up the heating system can become warm due to convection. However, as far as I understand it, for a vented heating system, there should always be two header tanks. Otherwise anti-corrosive chemicals from the heating system could end up in the water feeding the hot taps, and cold taps of hand basins (this cold water isn't supposed to be drunk because it came from the header tank and can have all sorts of dust and dirt in it!). In any case, hot water expansion shouldn't cause an overflow unless the ballcock is faulty or it's set in such a way that the water level in the tank ends up being too close to the level of the overflow.
© 2014 Eugene Brennan
Eugene Brennan (author) from Ireland on July 24, 2020:
Thank you, that made me smile on a Friday when everything was going wrong!
Medford1 on July 24, 2020:
That a very nice and professionally done illustration thank you so much, so glad to see people like you exist and spend their time helping others. you are a credit to human being thank you
Rad1620 on June 15, 2020:
Thank you Eugene, the water coming from the taps is pure clean, I did think that the coil might be perforated but the water from the taps is good.
There is a very small amount of silt sitting on the bottom in the header tank, I have churned this up and made the water in the tank brown but it did not show in the taps, it did appear when I drained the system.
The tank is overflowing as I write, the level increased about 6-8" since I drained yesterday and the cooker was only running for about 20 minutes to heat water, I am baffled.
Today I am going to change the ballcock valve and the circulating pump and stat. and watch what happens then. The smartphone is a brilliant idea, I will try it also.
As you said I will have to look into the possibilty of the coil in the copper cylinder.
Again thanks a million Eugene, really appreciate your time and help.
Eugene Brennan (author) from Ireland on June 15, 2020:
If the cooker is heating a hot tank via a coil, I wonder could the coil be corroded/leaking? Then water from the main cold tank that feeds the hot tank could be leaking through the coil into the heating system. The water level in the cold water tank in the attic would be higher than the level in the small tank and would eventually overflow it.
These coils are copper and fittings are brass, so a leak would be unusual.
Eugene Brennan (author) from Ireland on June 14, 2020:
Maybe setup a smartphone to do a timelapse video, taking photos every 5 minutes or so? You might catch what happens.
Rad1620 on June 14, 2020:
Yes, very strange, as there is only 1 outlet pipe, I am thinking of putting a non-return valve on the outlet pipe to eliminate that.
Eugene Brennan (author) from Ireland on June 14, 2020:
Strange though because if water spurts or expands up into the tank, water should flow down into the heating system to replace it. So there should be no net increase in level. You say you tied up the ballcock and water level still increased. So water must be coming from elsewhere?
Rad1620 on June 14, 2020:
Yes, it is the small expansion tank for the heating system and not the big tank, the overflow just started out of the blue a couple of weeks ago, nothing changed in the house, first water problem in 23 years in the house.
Eugene Brennan (author) from Ireland on June 14, 2020:
Sounds as though the water is spurting up into the tank, maybe helped by the circulating pump. I presume this is just the small expansion tank for the heating system, not your main cold water tank if you have one?
Rad1620 on June 14, 2020:
Thank you for reply. I can see the ballcock valve, there is definitely no drip, I have checked the ball itself, no water inside it.
Yes, it only happens after a couple of days of running the cooker, takes a bit longer when the pump is running at the lowest speed.
When I drain the water off to lower the level in header tank, the water is clean when I have the zone valve set to heating water and slightly brown when zone is to rads.
The pipe stat is working well, I wonder is the pump faulty, can't hear any rough noise from it, no air locks as I can bleed it easily.
Should there be a non-return valve on the outlet feed from header tank, I don't see any?
I have actually tied up the ballcock valve for a few days and it still overflowed.
I drained the system yesterday down to ballcock level, cooker has been running only a few hours since and now the header is just up to overflow level.
Thank you so much for the help.
Eugene Brennan (author) from Ireland on June 14, 2020:
A tiny trickle could overflow the tank in a couple of days. If you pull up the arm on the valve, it may shut off, but the float mightn't be able to exert enough force if it's a hollow ball and any water has leaked into it. When the valve shuts off, can you see the outlet from the valve and is water definitely stopped? Sometimes valves had silencers or other baffle arrangements that fed straight under the water surface, but this is prohibited now because of the danger of water siphoning back into the supply. Alternatively the valve could be leaking intermittently or possibly when temperature changes. Does the problem definitely only occur when the cooker is used? Possibly when water is heated and maybe starts to boil in the boiler of the cooker, bubbles of steam push the contents of the expansion pipe into the tank, spurting upwards, rather than the water just slowly expanding into the tank. Maybe watch what happens when the cooker has been running for a long period.
Rad1620 on June 14, 2020:
My header tank is overflowing, the ballcock valve is not dripping, I have watched the tank for long periods and cannot see any water from expansion pipe, yet the tank is filling, radiators are all bled and working great, I can also heat water perfectly.
I am using an oil fired cooker for all my heating needs. I have set the circulating pump to 3 different speeds, makes no difference.
I have drained the header tank and allowed it to fill to ballcock level, no drips, this level gives me about 6-8" to reach the overflow. The water will eventually reach the overflow after 2 days of using the cooker for a few hours. Thank you for reading this
Eric Lewis on April 07, 2020:
Great photies and I understood the wording and found it sound advice. Eric Lewis says thanks very much
Eugene Brennan (author) from Ireland on August 15, 2018:
You can click on the button in the left sidebar. The one with the orange circle and "P" in the centre. You need to have a Pinterest account first though.
Monica Pinchen on August 15, 2018:
Thank you for this very useful information. If I could post on Pintrest I would, unfortunately I don't know how to do so.
Eugene Brennan (author) from Ireland on June 03, 2018:
Does the float cut off the flow when you push up on it with your hand?
Is it rubbing against the sides or end of the tank.
Could the float be punctured?
Stephen Godwin on June 03, 2018:
I have checked all the remedies mentioned and there seems to be no problems with any of these My problem is that the small edder tank continues to fill and overflow there is no leaks anywhere and I changed the ballcock just in case, I take water out of this tank about 2ltrs twice a. Day maybe more does anyone recognise this problem or can suggest any remedies to stop this problem Thanks Steve
Eugene Brennan (author) from Ireland on March 01, 2018:
It depends on the degree of freezing Clare. If water on the surface freezes, the ballcock float won't drop to allow water in. So you'll eventually lose cold feed to your toilet, bath, shower and wash basin and also hot feed as the tank empties. There's a certain amount of "give" in plastic, so a some freezing on the surface isn't a big deal. If all the water in the tank freezes, it could probably stress the tank and damage it. During extended snowy/freezing weather, leave your trapdoor open, and radiators on upstairs to allow some heat to travel up into the loft to prevent any further freezing of water in the tank. Break any ice around the float so that it can move up and down.
Clare on March 01, 2018:
What should you do if you cold water tank freezes over? Is it a cause for concern? Can it effect the tanks integrity?
Eugene Brennan (author) from Ireland on January 13, 2018:
Great! Thanks for the feedback Sean, at least I have one happy "customer"!
Sean on January 13, 2018:
Great article. I was considering calling a plumber but this article left me in no doubt that I could do it myself. The plumber wanted €120 but I bought the washer for €0.50!! It took me less than 30 mins despite very limited access to the attic space, tank and valve.
Marina from Clarksville TN on December 13, 2017:
Very well written article. We don't have a cold water tank but it is useful for those who do.
Charles on December 13, 2017:
Thanks, brilliant hub, very detailed. Gave me confidence to do it myself. Just wish I had knee pads in my work trousers, kneeling on those boards at an awkward angle not good!
Eugene Brennan (author) from Ireland on October 23, 2017:
Hot water will run off from the hot tank quicker than the cold tank will fill. Now this could be because the pressure of the incoming cold water up in the attic is less than the pressure of the hot water (which is created by the pressure head of the cold tank). This might be possible if the tank feeding your home is one of the older concrete types on pillars not much taller than a house and you're not much lower than it, but unlikely if it's up on a hill somewhere. The reason the cold tank seems to continue to fill after you've run the hot water is because hot water flows out fast from the hot tank, while the level of water in the cold tank only drops maybe an inch or two. So the ball only drops a bit and the valve only partly opens and the water trickles in.
Some valves are noisier than others so probably you should have bought a "silent type".
Once upon a time you could connect a pipe to the outlet of the valve, exiting under the surface of the water, so that water flowed through it into the tank and didn't may gushing noises or do the interminable drip drippy thing all night (Chinese water torture!). However this sort of thing is against regulations because of the danger of water siphoning back into the supply lines if they empty during a water cut-off event. There must be a gap between the surface of the water and the outlet of the valve. I've seen a suggestion somewhere that you can use a piece of waste pipe standing on end in the water, but raised from the bottom so that water can flow in or out and also raised a little from the surface of the water. When water drops down it echoes in this stilling chamber which has smaller dimensions and contains the sound. I don't know how effective this would be, or how you would hold the pipe in place, plus it would have to be out of the way of the float arm so that it isn't prevented from dropping.
Tania on October 23, 2017:
I appreciate your article thank you! I am a lady with little plumbing knowledge but lots of plumbers who charge a fortune and don't fix the job!!! So I decided to change my cold tank valve as I have very noisy pipes when running hot water either upstairs or downstairs (it is not banging, just very loud gushing/whistling noise). After changing the valve it is still noisy, if I push the float down or push it up the noise stops. I believe it is something to do with the cold water not filling the immersion heater as quickly as the hot water runs off. If my theory is correct, do you know how I may resolve this problem. Many thanks for your help. Tania
francis andrews on September 13, 2017:
i,m a plumber with 30 years experience ,don,t waste time buy a new ball valve.
Eugene Brennan (author) from Ireland on August 21, 2017:
Thanks Sam. I'll keep that in mind. How would you recommend getting access to the nipple without dismantling? Maybe stapling sandpaper to the end of a wooden rod?
Sam on August 21, 2017:
Excellent article, clear and easy to understand. One thing I would add though is if the nipple has become pitted and still not holding back water, a light sanding starting at 120 and working up to 400 grit will solve this problem.
Debbie on June 07, 2017:
This is brilliant - I'm going to do it myself. Great easy to follow pictures - thank you!
Tom Foster on April 15, 2017:
Super-clear article and pics - thanks - made me certain I didn't want to tackle such a corroded nightmare, call in the experts. Sad innit.
Eugene Brennan (author) from Ireland on January 15, 2017:
Well that's unfortunate! The problem with these stopcocks is that the spindle or shaft which joins to the gate in the valve is not very large diameter so if you get overenthusiastic and try to turn it backwardsw and forwards with a wrench, metal fatigue can cause the shaft to wring (just like bending a paperclip backwards and forwards).
You can try a few thinks. Firstly try tapping the body of the valve (use lots of small sharp taps, not heavy blows) This may separate the bond between moving parts and body.
Try heating the body of the valve with a hairdrier. Then try turning the shaft. This will expand the body a little and help to unstick it from the shaft and gate.
Thirdly you can try using a tightly fitting spanner (wrench) on the handle of the valve. It's unlikely you have a wrench this size so you could use a stilsons (pipe wrench) or water pump pliers. If the valve is below floor level however, the chances are that you mightn't be able to extend the handle of the wrench sideways in the hole. You could try removing the handle from the spindle of the valve (assuming the nut isn't itself seized into place!) The end of the spindle is usually of square section and you can fit a wrench onto this, or use a long or short handled vise grips
Cordoba on January 15, 2017:
Hi Eugene many thanks for your quick response. I've found the stopcock just hope its the main one, it was under a wooden cover in the living room near the kitchen followed your tip on how to locate, the cover was painted over and screwed down! The issue I have now is that is completely seized and I can't get it to budge at all, probably due to the hard water over the years. Do you know of any way to get it moving again? I've tried applying some oil to loosen it and some back and forth pressure with a wrench over a cloth and applying some elbow grease but nothing is working. There's very little chance of finding the external stopcock as the property is on a private road that's completely gravelled. Got to love old character houses!
Eugene Brennan (author) from Ireland on January 14, 2017:
Hi cordoba, sounds as if the main shut-off valve is only for cutting water to your sink plus other fixtures. If you follow the incoming feed to this valve, are there no other valves before it, perhaps outdoors or at a water meter in the vicinity?
I've never used the freezing method. There are two techniques, use a freezing spray or a refrigerating coil which fits over a pipe. The latter would allow you to shut off the water flow indefinitely. Just in case there are any issues removing/refitting the ballcock, it might be a good idea to freeze the pipework feeding the tank, then fit a stopcock in this feed pipe. This will allow you to work at a leisurely pace replacing the ballcock.