Dual Flush Toilet Converters: Do They Add Up?

Claire Moloney
Consultant
June 26, 2014

Water Efficient Toilets

If you have an older toilet, you may be wasting a lot of water and money. A dual flush toilet converter may be a simple solution that could really add up.

As mentioned in a previous article about water saving toilets, toilets are the biggest water drain in American households, accounting for almost 30% of the home’s water bill.

Currently, the U.S. standard for toilets is 1.6 gallons per flush (gpf). However, many older toilets can use 3-5 gpf, and some even use 6 gallons. If you have an older toilet, you may be wasting a lot of water and money. These costs can really add up, because you may be wasting nearly 4 gallons per flush, and water in the U.S. costs $2 per 1000 gallons. At an average of 3 trips to the bathroom per person, per day, that's 12 gallons wasted per day, or 360 gallons per month. So, each year, in a one person household, you're wasting at least $8.00. For more people in a home, this can add up quickly.

However, replacing the toilet with a more water efficient toilet can be expensive, ranging from $100-325 (according to CostHelper).

Therefore, you may be interested in a dual flush converter. Much cheaper than a brand new toilet, these converters can cut your toilet’s water use by up to half.

Dual Flush Toilet Converters

For example, the MJSI Hydroright Dual Flush Converter is one model of a dual flush retrofit on the market. It can be installed in 5-10 minutes without tools and has been shown to reduce water use by 30%. This retails for just $22.98 at Home Depot.

Let’s say you have a family of four. The average person flushes 2000 times a year, and let’s guess that half of them happen at home - meaning that a family of four flushes a total of 4000 times in the home each year.

Let’s calculate the payback period for this dual flush converter in a few scenarios:

Dual Flush Converter Savings
existing Toilet	Dual Flush Converter w 30% Savings	Savings	Payback period
5 Gallons Per Flush (GPF) = 20,000 Gallons Per Year (GPY)	3.5 GPF/14,000 GPY	6,000 Fewer Gallons ($12 savings/year)	1.9 Years
3 GPF/12,000 GPY	2.1 GPF/8,400 GPY	3,600 Fewer Gallons ($7.20 savings/year)	3.2 Years
1.6 GPF/6,400 GPY	1.12 GPF/4,480 GPY	1,920 Fewer Gallons ($3.84 savings/year)	6 Years

Clearly, the more water the toilet uses, the longer the payback period for the Hydroright (see chart). It would make more financial sense to buy a dual flush converter if you have an older, less water efficient toilet. However, compared to purchasing a new toilet, the payback periods are much shorter.

In a previous article, using the same family of four and same baseline annual water use, replacing an older, 4 gpf toilet with a new low flow toilet would take 11.8 years (for a 1.6 gpf toilet at $227) to 16.7 years (for a 1.28 toilet at $364).

Therefore, buying a dual flush converter will have a much shorter payback than buying a new toilet in almost every case (see chart).