Water - Conservation in the Home

Frequently Asked Questions

1. How do I fix a leaking tap?

Check out here for full details on how to fix a leaking tap

2. How do toilets work?

The mechanisms of a toilet are explained here, with a handy diagram that shows what happens when you flush a toilet.

3. How much water does my toilet cistern hold?

To find out what the capacity of your toilet cistern is, you can do the following: Mark the level to where the water fills. The next time the toilet is used, before flushing, take the lid off the cistern. You may need someone’s help at this point. Hold the position of the float - this will stop the cistern refilling automatically after you flush. Flush the toilet. Use a vessel that measures 1 litre – this can be a measuring jug or an empty (washed) milk carton or drink’s bottle. Measure a litre of water and pour it into the cistern. Continue to do this until the water in the cistern reaches the marked level, counting the number of litres as you do this. Release the float – no water should flow into the cistern. Replace the cistern lid. Now you know how much water your toilet cistern uses!

4. How do I test to see if my toilet cistern is leaking?

Sometimes water leaks from the toilet cistern into the toilet bowl. To tell if your toilet cistern is leaking, place a few drops of food colouring in the cistern. Wait 15 minutes. If the colouring appears in the bowl, there is a leak. Alternatively, hold a piece of toilet paper against the back of the inside of the bowl. If it gets wet, it would again indicate that you have a leak. A leaking cistern can waste 16,000 litres of water a year.

5. How do I fix a leaking toilet cistern?

Note: Please keep in mind that all toilets are different. If you are unsure or are uncomfortable about repairing yourself, call your local plumber.

There are two common reasons for a leaking toilet cistern:

  1. The flush valve needs replacing. The flush valve is lifted when you pull the toilet handle, releasing the water into the toilet bowl through the drain hole. If the flush valve does not fit into the drain-hole after the flush, a small amount of water could continually leak into the toilet bowl. Click here for instructions on how to replace the valve:
  2. The filler valve is not working properly. The filler valve is released when the toilet is flushed and water fills into the cistern. As the cistern refills with water, the filler float rises and when it reaches the top, it shuts off the filler valve. If the float does not rise to the top, then the filler valve will remain open and water will continue to flow into the cistern. To avoid flooding, the overflow pipe will discharge this water into the toilet bowl. Here is some information on how to repair this.

6. Is my toilet suitable for a water-saving device?

Most toilets installed before 1991 are likely to have a cistern capacity of 9 litres or more. If this is the case, then you should be able to install a water-saving device and save up to 3 litres per flush. Toilets installed between 1992-2001 are likely to have a cistern capacity of 7.5 litres. You can install a water-saving device that could save you 2.5 litres per flush. Toilets installed after 2001 could have a cistern capacity of only 6 litres. If this is the case, then you do not need a water saving device, especially if it is a dual flush. A quick search on the internet will find you more information on relatively cheap water-saving products that are available.

Useful Links

Follow this link to find out more about Rain Water harvesting and water butts available at Irish Water's website.

The following websites provide information on water preservation, conservation and water aid and reducing water usage in the home, office, school, garden etc.


If you have a recommendation for inclusion on this page about water conservation and preservation or would like your organisations website to be included, please email greenhome@eeu.antaisce.org