How Low Can You Flow? Myths and Realities of Low-Flow Toilets

Many of us are aware that one of the simplest things you can do to go green is save water. Take shorter showers, install aerators, keep the faucet off while brushing your teeth.

But low-flow toilets?! When it comes to flushing, well… many of us draw the line.

When flush toilets made their first debut in the 1800s, Americans used a whopping seven gallons of water per flush. As technologies improved and concerns over water conservation grew, however, toilets became more efficient. Eventually, a federal law passed in the early 1990s mandated all new constructions to install 1.6-gallon toilets.

Unfortunately, while the decrease in toilet capacity saved water, it also increased concerns of… well… performance. Early low-flow toilets faced unfortunate problems with clogging and “residuals,” leading to a bevy of bad press. Luckily, the bad press led to design changes that have revolutionized low-flow toilets. With today’s eco-friendly versions, we are no longer doomed to janitorial duty after every flush. And we can save up to 27,000 gallons every person, every year.

Single-Flush Low-Flow Toilets
Most single-flush low-flow toilets rely on gravity to pull solids out of the toilet bowl. Less water means less power through gravity, so design improvements have included larger drains to reduce clogging, and redesigned bowls and water flow to reduce “residuals.”

Some manufacturers have improved performance of single-flush toilets by pressurizing the smaller quantity of water, or by using pressurized air to force solids out. Both require electricity to function, however, so they are technically less sustainable (and will likely save you a little less money) than the gravity-assisted versions. 

Dual-Flush Low-Flow Toilets

A water-savvy Australian developed another technology that gives you the option of saving even more water. Pull the handle one way, and an efficient 0.8 gallon will flush away liquids. Need a little more force? Pull the handle another way, and a useful 1.6 gallons will do the trick.

Choosing a Model

So… with all of the choices on the market these days, how exactly do you choose a low-flow toilet that’s right for you? Like anything, shop around. Performance is key, so check out the Maximum Performance Testing results (a widely accepted third-party testing program) as a start. For other really useful considerations, check out the Green Home Guide’s page on low-flow toilets.