Product Description

The Interflush is a DIY retrofit device that converts standard, single-flushing WC siphons into water-efficient interruptible flushing toilets. The patented kit is designed to fix on top of existing plastic WC siphons and connects to the front-mounted flush handle. The Interflush Kit works by introducing an ‘air brake’ on top of the siphon, which is closed when the handle is down and open when the handle is up. Because a siphon stops flushing when air is allowed to enter, the siphon will only flush when the handle is held down. Therefore, attaching the Interflush kit to a siphon gives the user full control over the volume of water being flushed.

To operate, simply press the handle, hold down until the pan is clear and then let go.


Of the 150 litres each person typically uses per day, approximately 60 are used for toilet flushing. This makes the toilet the appliance guilty of using the most water in any given household. Trials have shown that attaching the Interflush kit to a siphon saves an average of 47% of the flushing water. In monetary terms this means that water bills could be cut by around 18-40%: approximately 18% for households and up to 40% for businesses without baths, showers, washing machines etc. The Interflush kit saves the maximum possible volume of water each flush and offers the user very short payback time.

The Interflush kit is simpler to use than any other device on the market – simply press the handle, hold down until the pan is clear and let go. All other flushing systems and retrofit devices flush fixed volumes of water, meaning that unlike the Interflush they do not completely avoid waste. Dual flush toilets, for instance, only offer half or full cistern flushing. Similarly, cistern displacement devices such as the Hippobag or Save-a-Flush bag reduce one fixed volume of water down to a lower fixed volume, often not leaving enough to clear the pan and thus necessitating a second flush (double-flushing). The Interflush’s unique design allows users to control exactly how much water is flushed each time; it is the only water saving toilet device that allows you to use the exact volume of water that is required to clear the pan.

What about putting a brick in the system?

In a press release titled ‘Water Efficiency in the Bathroom’ (2006) the Bathroom Manufacturers Association warned against putting any object in the cistern to reduce the amount of water it stores, because a toilet that was designed to flush on 13 litres will probably not clear the pan if you use a lower volume. This often results in having to flush a second time, which wastes more water than a toilet without a ‘water saving’ device.

Unlike cistern displacement devices, Interflush does not tamper with the recommended volume of water stored in the cistern; the water level can remain set to the line as marked on the back of every cistern, ensuring that there is enough water available should you need it and eliminating the need for double-flushing. The unique design of Interflush allows you to use as much, or as little, water as is required to clear the pan.

  • Flushes only what is needed instead of the whole cistern (or other fixed volumes), wasting none.
  • Saves households around 18% on water bills.
  • Manufactured in the UK, with minimum material use (all parts recyclable).
  • Designed to fit the majority of siphons and cisterns with front-mounted handles.
  • Simple, self-teaching and easy to learn operation – tests show that correct and consistent operation is embedded after only 17 flushes.
  • A better alternative to the Dual Flush and the Hippo bag, both of which waste water.

Click here to buy now

Click here to download PDF information pamphlet

Note: If your toilet is not flushing properly (ie. if you have to crank the flush handle), there may be a problem with the diaphragm or return spring. If this is the case, it is advised that the siphon be completely replaced. An Interflush kit will not make a poorly-flushing siphon function any better.

For fitting instructions, click here.