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

Welcome to this guide to replacing the bottom entry fill valve in your toilet cistern.

Below you will find step-by-step instructions on how to change a bottom entry fill valve in a toilet cistern, and a list of toilet manufacturers that this brass shanked, bottom entry, fully adjustable fill valve from FlushKING will fit.

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.

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  • Fits all toilet manufacturers (see below)
  • Fills from the bottom and is much quieter
  • Fully adjustable float to set the water level you need
  • Fully adjustable height to fit most cisterns
  • Saving water will save you money (if on a water meter)
  • More reliable than old ball valves with floats
TowelPlumbers GripsFlat head Screwdriver

Tools you will 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 a pair of grips, a flat head screwdriver and a towel.

If you are looking to replace just the fill valve then you will need one of the two products below. You can check what product you need by looking at your existing cistern and identifying where the flush is currently placed.

Type of toilet cistern Product you need Type of toilet

Top fixed button

Any toilet cistern with a water supply on either side as highlighted.

Side Entry Fill Valve

Side Entry Fill Valve

This fill valve will fit most toilet cisterns where the water supply connects to the cistern on the side, whether the hole is on the left or the right.

Bottom entry fill toilet cistern

Any toilet cistern with a water supply connecting at the bottom of the toilet cistern.

Bottom fill valve, adjustable with brass shank

Adjustable Bottom Fill Valve - Brass Shank

Cisterns that have the water connection connecting on the bottom of the toilet cistern will use bottom fill valves. The example used here is fully height adjustable, and has a robust brass connection shank. You can also use the adjustable bottom fill valve with plastic shank if you are looking for a cheaper alternative. And if you cistern is not limited on height, you can also opt for the basic standard bottom entry fill valve which is plastic shanked and non-adjustable in height.

It is a good idea, while you are isolating the water supply to your toilet cistern, to consider changing your flush valve as well. If you have an old syphon flush these are generally single flush and waste a lot of water. Below are the products you would need to change the flush valve. The flush valve is in two formats, a top-fixed flush valve and a fleximount cable flush. You can check what type of flush valve you need by looking at your cistern for how it flushes and compare it below.

Type of toilet cistern Product you need Type of toilet

Top fixed button

Any toilet cistern lid with flush button on the top & centre.

Top Push Button Flush Valve

Top Press Dual Flush Valve

This flush valve will fit most top-push flush button cisterns. It is recognised by the fact the cistern is fitted directly to the top of the toilet pan, and has a push button on top of the cistern lid as pictured left.

Lever flush cistern

Any toilet cistern with a lever flush in any of the positions highlighted.

Flexi Mount Dual Flush Valve

Flexi Mount Dual Flush Valve

This flush valve will fit most lever flush cisterns, and with its fleximount cable the flush button can be placed wherever the flush lever used to be. This is also the case with concealed cisterns that may be fitted inside cabinets or stud work with a button on the fascia or countertop.


Step by Step

Turn off the waterStep1: 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 matrix above to compare to your toilet cistern. For this how-to guide we will use the Brass shanked, fully adjustable height, bottom fill valve as it's the most universal and robust fill valve.

Locate the old bottom fill valveStep 2: When you look inside a bottom entry cistern you will see a fill pipe coming up from the bottom of the cistern with a float of some type either at the end of an arm or built around the pipe itself. If this is not the case, and your water pipe connects at the side of the cistern the principle is the same, but you need a Side entry fill valve instead, and follow the instruction guide you will find here.

Locate the service valve and switch the water offStep 3: Ok, now we are sure we are working on a bottom entry cistern, the first thing you need to do is to switch of the water on the isolating valve on the water connection (if your toilet hasn't got its own isolating valve you may need to locate your stopcock and turn off your water supply). You will need your flat head screwdriver and use it to turn the screw head on the isolator 90 degrees to the off position.

Towel out any remaining water to avoid making a mess when removing the old fill valveStep 4: Flush the toilet repeatedly to drain out any water in the cistern, and ensure the water is fully off by checking the cistern isn't filling again. You will need to use your towel to dry out any remaining water so that it is completely dry otherwise when you remove the old fill valve this water will escape as it is the lowest part of the cistern. Just soak it up and ring it down the toilet bowl, then place your towel under the cistern to catch any trapped water.

Disconnect the water supplyStep 5: Now you are ready to disconnect the water supply from the fill valve underneath the cistern. Take your grips (or an adjustable spanner) to the nut on the isolating valve or tap connector that is screwed onto the bottom 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.

Remove the back nut securing the old fill valveStep 6: You are now ready to remove the old 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.

You should now be able to remove the old fill valveStep 7: The fill valve should now lift out without any resistance at all, and make sure you remove any old rubber washers 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, as you will be need it to be smooth and clean to get a good watertight seal when the new FlushKING unit goes in.

Check and adjust the height of the new FlushKING fill valve to suit the cistern height.Step 8: Take out your new FlushKING adjustable fill valve and offer it up to the cistern so you can adjust the height to fit your toilet cistern. To adjust the height, push up the grey clamp ring just above the threaded part of the stem to unlock the adjustment thread, then pull the lower section down until it is at the correct height for your cistern. Once you are happy with the height, pull the locking ring back down to lock it in place. (Don't worry if it's not quite right, this can be done after it is installed.)

Lower the new FlushKING fill valve into position, ensuring the float is free to moveStep 9: Remove the back-nut from the new fill valve, making sure to leave the coned rubber washer in place as this will create the watertight seal at the bottom. Lower the new FlushKING valve into the cistern making sure that as you lower it the green float that is wrapped around the pipe is free to move up and down as this is the only moving part that needs clearance. Once you have the threaded end through the hole, check and adjust the height of the pipe again to fit under the closed lid.

Secure the fill valve in place with the back nut providedStep 10: Take your back-nut from the FlushKING fill valve and you will notice that it has tabs on it to make it easier to tighten by hand. You shouldn't need to use grips here as the design of the cone washer and the back-nut should create a watertight seal simply by hand tightening. So place the nut over the threaded brass shank and turn clockwise until the slack is taken up, check the cone washer is sitting central in the hole and then nip the back-nut up until it feels tight and offers resistance.

Reconnect the water supplyStep 11: Now it is time to connect your water supply back to the cistern by reconnecting the nut from the isolating valve or tap connector (although this is the perfect time to add an isolating valve whilst the water is off). Switch on the water and check for any leaks by running your fingers over every joint you have worked on. Once you are happy all is dry and there are no leaks, test the fill valve by flushing the toilet and allowing it to refill.

Adjust the float until you are happy with the water level in your cisternStep 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, which may be a plastic pipe exiting your cistern to a waste pipe away from the toilet or a modern internal overflow flush valve as pictured here with the FlushKING flex-mount flush unit. Once you are happy with the level, check underneath for any leaks. Now replace the cistern lid and you're done!

Fits all these toilet manufacturers' cisterns

Twyfords logo Fits most Roca Cisterns Fits most Ideal Standard Cisterns Fits most Armitage Shanks cisterns Fits most Ideal Cisterns Fits most Shires cisterns Fits most Lecico cisterns Fits most Macdee cisterns Fits most Thomas Dudley cisterns Fits most duravit cisterns Fits most Vitra cisterns Fits most Bauhaus cisterns Fits most Eastbrook cisterns Fits most Rhoper Rhodes cisterns Fits most Bristan cisterns Fits most Hudson Reed cisterns


Did you know?

Levels of Water StressThe 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.

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