How do I change a side entry fill valve in my toilet cistern?

Fill Valve

Welcome to this guide to replacing the bottom entry fill valve in your toilet cistern. Below you will find step-by-step instructions, a video guide and a list of toilet manufacturers that this side entry fill valve from FlushKING will fit.

Tools You’ll Need

You will find that FlushKING products are simple to fit without tools, however you will need to have tools ready to remove the old valve from the toilet. You will need:

  • Pair of grips
  • Flat head screwdriver
  • Towel

What product do you need?

You can check what product you need by looking at your existing cistern and identifying where the water supply is.

Side Entry Fill valve

If your toilet cistern has a water supply on either side as highlighted, you will need the Side Entry Fill Valve.


Bottom Entry Fill valve

If your toilet has a water supply connecting at the bottom of the cistern, you will need a Bottom Entry Fill valve.

Bottom Entry Fill Valve

Whilst isolating the water supply to the toilet cistern, it is usually a good idea to consider changing the flush valve as well.

Video Guide

If the toilet in these instructions or video does not look exactly like your toilet cistern, don't worry! The mechanics inside are all very similar.


Step-By-Step Guide

Bottom Entry Fill Valve

1. Check that you order the correct fill valve for your cistern type, when you have removed the cistern lid, look inside. Does your water connection pipe enter it at the bottom of the cistern? left or right makes no difference, it will either be from the bottom or the side. Use the comparison above to compare to your toilet cistern.

Bottom Entry Fill Valve

2. When you look at your side entry cistern you will see a water supply pipe entering the cistern from either left or right, and the same applies for a concealed cistern, a close coupled toilet or even a low level toilet. On the inside of the cister, connected through the wall of the cistern is the fill valve, if this is letting water by constantly, or not opening even, it is time to replace it with a more efficient bottom fill side entry that allows you to adjust the water level and fills through a solid pipe from the bottom up making it a lot quieter. This cistern is fitted with on old Torbeck fill valve, but this guide is the same if you have a long arm with a float.

Bottom Entry Fill Valve

3. The first job is to locate the nearest isolation valve or stopcock and turn off the water supply to the toilet. You should have an isolation valve as pictured, which may be straight or bent but will have a flat head slot to turn 90º to switch it off (if you don't have one, now may be the time to fit one whilst the water is being turned off. In the meantime locate your house water stopcock (usually under the kitchen sink) and turn off the water.

Bottom Entry Fill Valve

4. Flush the toilet to drain out any water in the cistern, and ensure the water is fully off by checking the cistern isn't filling again. You shouldn't need to towel out any water that is left in this installation as the fitting connects in from the top. If you want to do it, it is a good idea to remove any debris or scale that may have built up in the bottom of the cistern.

Bottom Entry Fill Valve

5. Now you are ready to disconnect the water supply from the fill valve on the outside of the cistern, take your grips (or an adjustable spanner) to the nut on the isolating valve or tap connector that is screwed onto the side of your fill valve and turn it anti-clockwise till it loosens enough to undo the rest by hand. You will get a small amount of water that is trapped in the pipe leak out, so make sure your towel is below to catch this.

Bottom Entry Fill Valve

6. You are now ready to remove the old, faulty fill valve as it is only held into the cistern with a plastic back-nut (normally plastic to prevent the cistern getting damaged). You should be able to undo the back-nut by hand as it only needs to be hand tight, but if it is being stubborn due to old sealants, use your grips to loosen it. remove the nut completely and discard as your new unit will have its own back-nut in the box.

Bottom Entry Fill Valve

7. The fill valve should now lift out without any resistance at all, and make sure you remove any old rubber washer from inside the cistern that may be perished and stuck around the hole you now have in the bottom of your cistern, Take a bit of time now to clean around the hole inside the cistern and also underneath it, you will be need it to be smooth and clean to get a good water tight seal when the new FlushKING unit goes in.

Bottom Entry Fill Valve

8. Remove the white plastic back-nut from your new FlushKING fill valve and select the black rubber washer that fits best into the hole on your cistern, there are two to choose from, a cone washer and a flat washer and between them they should seal all inlet holes available. Place the chosen washer on the threaded shank with the flat side to the valve body.

Bottom Entry Fill Valve

9. Place the threaded shank through the hole in the cistern and secure with the plastic back-nut firmly, but hand tight so as not to crack the cistern, the rubber washer should seal the gap this way. If you should find any weeping once water is switched back on, check the seating of the washer and tighten to ensure it seals.

Bottom Entry Fill Valve

10. Now reconnect the water supply by screwing the female nut back onto the plastic threaded shank, check your service valve or tap connector to make sure the washer is in good condition, if it is old it may have perished. Once you have reconnected it give it a wipe around with a piece of tissue so you can tell if the join is leaking or not once the water is turned on.

Bottom Entry Fill Valve

11. Turn the water supply back on at the service valve or stopcock depending how you turned it off originally and wait for the cistern to refill. Once the water stops filling, check all joints to make sure you have no leaks, check around the water connection and the hole through the cistern. If you have had to wrestle off the old connection check all joints to make sure nothing has been disturbed such as the flush pipe connection to the pan.

Bottom Entry Fill Valve

12. At the top of your new FlushKING fill valve you will see a grey arm with a green dial on top of it, this dial is how you adjust the rise and fall of the float to set the water fill level, keep adjusting this up or down until the water settles at a level just below your overflow pipe, this may be a plastic pipe exiting your cistern to a waste pipe away from the toilet or a modern internal overflow flush valve. Once you are happy with the water level and checked underneath for any leaks you can replace the cistern lid and your done!

Compatible with

Compatible brands

Browse our range of fill valves here

Did you know?

The Environment Agency has developed a methodology for identifying and classifying relative levels of water stress in water company areas in England. The Government has used this map to designate areas of serious water stress for the purpose of accelerating water metering.