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How to Change a Bottom Entry Fill Valve

Matt Robinson | Updated on January 14, 2021
Toilet Cistern Fill Valves

Is your toilet cistern filling up really really slowly? Is your cistern constantly filling with water? Are you hearing strange noises coming from your cistern? If you can answer yes to any of these questions it might be down to a faulty fill valve.

If you have an old ball valve and arm type mechanism in your toilet cistern it’s worth noting that these are pretty out of date and don’t work as efficiently as the newer fill valves. Another great thing about modern fill valves is that you don’t need an external overflow pipe. This is because if the valve were to fail the excess water would be released directly into your the toilet pan.

At Palace Plumbers we recommend purchasing a fully adjustable fill valve with a brass shank on the bottom. These are are the best type of bottom-entry fill valve because the brass shank makes them stronger than their plastic counterparts, and being adjustable means that you can set your water level to the optimum level to save money on your water bill.

If you are confident enough to tackle the job yourself please read on. Our easy-to-follow guide on how to change a bottom entry fill valve covers all the necessary steps to successfully replace your old fill-valve with a new adjustable valve.

If you’d feel more confident in letting a professional plumber complete the job please don’t hesitate to get in touch.

Steps involved

  • 1. Turn off water supply to fill valve
  • 2. Flush loo and towel out remaining water in cistern
  • 3. Undo feed pipe with adjustable spanner
  • 4. Take out the old valve
  • 5. Put the new valve in
  • 6. Switch the water supply back on
  • 7. Test for leaks

Tools needed

  • 1. Screwdriver
  • 2. Adjustable spanner
  • 3. Grips

1. Turn off the water supply to the fill valve

Isolation Valves

Whenever you are working on your toilet it’s necessary to isolate the water supply to your cistern.

If the original installation has been carried out by a forward-thinking plumber you should have isolation valves on the inlet pipe that you can simply turn a quarter-turn with your screwdriver.

If you don’t have an isolation valve (shut-off valve) locally it may be necessary to turn off the water from your main stop-cock.

2. Flush the loo and towel out the remaining water in the cistern

Once the water to the cistern has been shut-off you’ll need to flush the toilet to empty the cistern. There will always be about 1″ of water left at the bottom which you’ll need to remove by soaking it up with a sponge or towel.

3. Undo the feed pipe with an adjustable spanner

With the cistern empty, it’s time to undo the feed pipe so that you can remove the cistern completely from the pan.

Maybe place a towel on the floor and even a bucket to catch any water. You may need to also grip the body of the valve (inside the cistern) if the nut is tight. A small amount of water will escape and should fall into the tub/bucket.

4. Remove the old valve

Undo plastic nut under the cistern that holds existing valve onto the cistern. Once this is wound off should be able to remove the entire valve

5. Install the new valve

See what adjustments need to be made and also what the water level will be etc. take it out and adjust to the height you?d like.

Always make sure that the seat that the rubber washer will sit on is nice and clean so that you get a great seal. Pop the new nut on the brass shank at the bottom. Tighten it up. Retighten the water supply. Switch water back on. Test for leaks. Also test for water level and see if further adjustments are needed.

Before you tighten it ensure that the body is pointing in the right direction and is unobstructed.

Reseal the water connection and make sure you have a nice watertight seal.

6. Switch the water back on

This is simply a case of opening the isolation valve that you shut off during the first step of the process.

7. Test for leaks

Always test for leaks before you put your tools away and head off for a well-deserved cup of tea. Using a dry paper towel or piece of toilet roll to wipe over the area will quickly detect any areas that are weeping or leaking.

This is also a good time to check the performance of your new fill valve by how quickly the cistern is filling up, and how fast the valve shuts off to once the cistern is full to it’s desired capacity.

Once you are confident that the cistern is leak-free simply pop the cistern lid back on and voila.

Talk to our team for help and advice or to book

Call 020 3880 5666

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