We recently wrote an article on low flow toilets and the advances in toilet technology requiring less water to move waste. There are currently two broad categories in efficient toilet technology

1. Low Flow Toilets - These are the standard toilets in most homes. They consume 1.6 gallons per flush.
2. Ulta Low Flow Toilets - These are a more recent toilet technology. The consume on average about 0.8 gallons per flush. Most Ultra Low Flow toilets have a dual flush system one for solid and one for liquid waste removal. The amount of water per flush is an average of both flush modes.

When considering whether to install ultra low flow toilets as part of a new construction or replace existing low flow toilets with ultra low flow toilets, the thought of payback period comes to mind. Ultra Low Flow toilets are typically more expensive than regular Low Flow Toilets. How soon will the investment in the Ultra Low Flow toilets pay off?

We performed a simple computation using some assumptions on toilet usage. The following are the assumptions we made;

* Usage based on a household of 4
* A single toilet is used in the household
* All household members are out of the house during business hours in the work week.
* 5 Toilet flushes per weekday per person in the house (out of the house during business hours)
* 10 Toilet flushes per weekend day per person in the house


We did a comparison between a standard low flow toilet with a flow capacity of 1.6 gallons an average retail price of about $199.00 compared to an ultra low flow toilet with a flow capacity of 0.8 gallons and a retail price of about $299.00
We also focused our payback period on the extra cost for an ultra low flow toilet compared to a low flow toilet, since going without a toilet in a household is not an option.

We also did not include any installation costs in the computation.
We assumed a 1:1 volume of water consumed to sewer expelled. In our article about dual water meters, you can read why this is the case with most water utility companies.
Also note that the costs of water consumed and sewer vary, with the latter often being more expensive.



From our computation it would take 2.2 years to recoup the difference with the above assumptions.

Some people may think that is quite a long time, however keep in mind the other major benefit of making the switch to ultra low flow toilets - it drastically reduces the amount of water used in the household, which is good for the environment. In our example thats over 12,000 gallons of water saved a year. While this may not directly translate into dollars in your pocket, it helps the greater good.

Of course as our previous article mentioned, ultra low flows may not be as efficient should you find yourself requiring an extra flush to get things going.