I recently removed a tube of toothpaste from the innards of my toilet, which got me thinking about replacing the ol’ 13 litre/flush (3 1/2 USgals/flush) beheamoth. These thoughts co-incided w/ the arrival of my City of Fredericton water bill, which also got me thinking about the potential savings of upgrading my sewage conveyance device.
There are several models of low-flush toilets. The standard water closet is now 6 Lpf. This is considered the baseline of any calculations towards LEED water efficiency credits. Any toilets I specify in commercial or institutional buildings are at least this type or better.
Toilet manufacturers have pushed the envelope on the 6 Lpf number, and many now offer models in the 4.8 Lpf range. Some toilets at this flush require assistance from compressed air within the tank. These are called “Pressure-Assist” toilets.
An innovation from Australia is the dual-flush toilet. These units allow you to use half or full flushes depending on what you are flushing. These toilets are standard in Australia, and are typically found in the 6/3 Lpf range. They are becoming more and more common in North America.
The City of Frederiction charges $0.53 per cubic metre of fresh water (incoming), and another $0.53 per cubic metre for sewer (outgoing). It thus costs $1.06 for every 1000 litres of water you consume. Using my 13 Lpf toilet as a model, I calculated the water and monetary savings for installing a new toilet according to methods laid out by the Canadian Green Building Council in LEED Credit WEc2 (Innovative Wastewater Technologies). The CaGBC assumes each occupant in the home uses the toilet 3 times per day (1 solid, 2 liquids).
The final column, the yearly percent water reduction, assumed quaterly $100 water bills (as my household currently receives). I won’t be rushing out to replace my toilet based on a 6 year payback. It does make sense, though, to replace the toilet with a more efficient model once replacement is necessary.
