Every time you take a shower, brush your teeth or do a load of laundry, you’re letting water — one of Earth’s most precious resources — just swirl down the drain. Instead, what if you reclaimed that water and reused it to flush toilets and water the flowers?

Some municipalities, homebuilders and water-recycling manufacturers are increasingly making that a viable option. In the United States, where the average household uses more than 300 gallons of water a day, one of the greatest untapped resources is grey water.