Water treatment is one of the most important things you can do to save on water bills, according to a new study.

A survey by the water and waste management company WaterSense found that about half of households that use their water for bathing and washing are also likely to pay more for water treatment if they don’t have to spend money on a filter.

“Our findings show that water treatment is the single biggest factor impacting our water bills,” says Sarah Hodge, a senior water analyst with WaterSense.

She adds that people should spend as little as $1 a month on water treatment to ensure they have the most efficient way to dispose of their water.

“It’s the one thing people can do that can be a huge cost saving, especially if you’re a family with children or if you have older kids,” says Hodge.

To make your bathroom more water friendly, follow these steps: Waterproof all sinks and toilets.