Some toilets send more water down the drain than necessary for an effective flush. There are practical steps you can take to reduce the waste of water in your toilet whilst ensuring that your toilet flushes clean.
The old, single flush toilet can use up to eleven litres of water per flush. This is much more than what is needed to effectively get rid of waste. Even the old dual toilet systems designed in the early 1980s use an excess of water to get rid of waste – 5.5 litres for a half flush and eleven litres for a full flush.
High efficiency toilets (HETs) have been carefully designed to get rid of waste with much less water. These toilets use as little as 3 litres for a half flush and 4.5 litres for a full flush. This saves more than 50 per cent of the water lost through the less efficient, earlier designs.
| Flush | Volume |
|---|---|
| Old single flush systems | Up to 11 litres |
| Old dual toilet systems (1980s) | 5.5 litres half flush /11litres full flush |
| High efficiency toilet systems (HETs) | 3 litres half flush / 4.5 litres full flush |
| Average flush in New Zealand | 6.4 litres |
20-25% of water used in the home is being flushed through the sewer pipes. On average, each person flushes their toilet five times a day, sending approximately 6.4 litres of water down the drain with each flush. That’s three and a half buckets of water a day per person.
Being efficient about the use of water in the bathroom and toilet reduces the demand on local water supplies. Households that are charged for their water through metering, such as Auckland, will see a direct benefit in saving water in their toilet. Households not metered will also benefit. By reducing the demand on local water supply we can delay or reduce the need for councils to have to build more infrastructure to meet increasing water demands. This can help in saving money on rates as well as reduce our impact on the environment – building structures like dams cause huge disruption to the local ecosystem (see water for more information).
Test for leaks! Is your cistern needlessly wasting water through a small leak? Put a few drops of food colouring in the cistern. Leave it for between twenty minutes and two hours. If the colouring leaks into your toilet bowl before flushing you have a leak. It’s time to ring a plumber who can fix the leak and save water (and money).
Below are some options you can look at to make your flush more efficient:
| Make your flush more efficient | Water saved (per flush) |
Advantages | Cost |
|---|---|---|---|
| Refit your bathroom with a high efficiency toilet | Approximately 7.5L | Permanent | Plumber, toilet |
| DIY: reduce the volume of your flush with a bottle (see below). | 1-2L | Fast and Easy | Free |
Refitting your bathroom with a high efficiency toilet is the most straight forward method for reducing the water used by your toilet. If you are shopping for a high efficiency toilet keep an eye out for toilets with WELS (Water Efficiency and Labeling Standards) stickers on them. WELS stickers indicate the effectiveness of the toilet by the number of stars that are displayed. The more blue stars on the label, the greater efficiency the toilet has – a rating of 4-6 blue stars is really good. Note: this labeling system is not mandatory in New Zealand until July 2009 so if in doubt ask the shop assistants and they should be able to point you in the right direction.
If you are not planning a bathroom renovation but want to increase your water efficiency, this can easily be done by filling a bottle with water and placing it in the cistern. Experiment with the best size bottle for your toilet (600ml, 1 litre, 2 litre) to ensure that the flush remains efficient. The following video demonstrates how this may be done.
Q. What if my toilet doesn’t flush properly after I put a bottle in the cistern?
A Objects like water bottles may change the shape of water in the cistern and this may effect the flow of water and reduce the effectiveness of the flush. If any problems occur the objects can be easily removed.
Q. Can I use a brick in my cistern?
A. Bricks have been used in many toilets but there is the chance that they could crumble and cause blockages in the pipeline.
Q. Are there some toilets in which a bottle will not work?
A. Yes, high efficiency toilets are designed to work on the lowest volume possible for their shape so you will likely compromise the efficiency of these toilets by fitting a bottle in the cistern.
Q. Saving 2 litres of water by putting a bottle in the cistern doesn’t sound like much, why should I bother?
A. Two litres of water may not sound like much, however, that equates to 10 litres of water per day (2L x 5 flushes). In a year this totals at 3,650 litres of water (405 buckets per person). For a four person household that’s a saving of 14,600 litres, that’s 14.6 tonnes of water saved each year!
