every six months to a year I experiences no cold water to my upstairs bathroom

[Richard2019]

Thank you for taking the time to read my question; I am desperate for professional advice.
In the last two years, my bathroom's water pressure has gotten low, but was totally fine before. Now, I often experience low cold water pressure for a few days. After which, there is no cold water to my upstairs bathroom, at all.

By chance, I found out that draining the cold water tank in the loft, then refilling it with water would fix the problem.

So when the next times the water pressure was low, I tried to use the same method. It worked twice, but just before Christmas the problem happened again and the same trick didn't seem to work; please help!
Thanks in advance and Happy New Year!

 

[terryplumb]

Sounds like air is entering your pipework ,causing an air lock. The ball valve ,or the supply of water to it , is not allowing the loft tank to fill fast enough when large amounts of hot and cold water are run off simultaneously ,like when fully filling a bath.

 

[dilalio]

As Terry states, its very likely air on the cold supply. Try using the hot blocked off at an open hot outlet to clear the cold airlock, else you'll need to use a hose on the kitchen or outside tap to force mains pressure up tank fed cold feed. You can try and do this using a kitchen mixer to get mains up the hot and then upstairs at a tank fed mixer to get the relayed mains over to the cold but either 2 persons or a jig required.

 

[terryplumb]

Do you currently have no cold water coming from your bathroom taps ?
Is the loft tank full ?

 

[JohnD]

You might find it clears, over time, if you leave a tap open (while you are in the bathroom and watching it). Water may drip out, then dribble, then suddenly gulp and spurt and clear the airlock.

The airlock is more likely to happen when you have extra people in the house, or are running lots of water, especially baths. Do you have a pumped shower?

It may be that the ball-cock in your cold-water tank (cistern) in the loft is running slow. It's possible to repair them, but a new one is quite cheap, and less work to fit. A new one can also be quieter than an old one. Sometimes people part-close the main stop cock to quieten a noisy valve, and this reduces flow.

Can you post a pic of your existing ballcock in the loft?

If you can fill a jug, bucket or something by pressing down the float and timing it, you can calculate how many litres per minute it delivers. This will give useful clues.

 

[Richard2019]

As Terry states, its very likely air on the cold supply. Try using the hot blocked off at an open hot outlet to clear the cold airlock, else you'll need to use a hose on the kitchen or outside tap to force mains pressure up tank fed cold feed. You can try and do this using a kitchen mixer to get mains up the hot and then upstairs at a tank fed mixer to get the relayed mains over to the cold but either 2 persons or a jig required.

 

[Richard2019]

Thank you so much for your all speedy replies. the water is back to normal. Thanks for all your professional advice. When I kept the downstairs toilet sink tap open and continually flashed downstairs toilet a few times, it surprised me and cured the problem, just hope it keeps working.

Happy New Year !