Keeping your sprinkler on a timer can be a convenient way to keep your lawn watered, but it can also be horribly wasteful. If you're not around to switch the timer off during, say, a rain storm, you could end up running your sprinkler for no reason at all.

With California and many other states still experiencing severe drought, wasting water through automated sprinkler systems can cause major PR headaches for businesses and government agencies, as a McDonalds in Long Beach, California, found out the hard way last year. But one San Francisco Bay Area company believes that better tech can help save water by making sprinklers smarter.

As the system collects more data about your lawn and your climate, it uses machine learning to make predictions about how much water your plants need.

ETwater uses sensors to measure how much water soil can take and tries to deliver just the right amount. It's not unlike the 'precision agriculture techniques used by farmers. But instead of selling to farms, ETwater has focused its products on public parks, corporate campuses, and even residential lawns. You can lease the company's equipment, complete with the wireless service it depends on, for as little as $35 a month.

"People who have different zones in their yard, like flower beds or trees, people who really care about this stuff are attracted to our service," says CEO Lee Williams.

But ETwater's system doesn't stop at the soil. It uses environmental sensors to monitor factors such as temperature, soil type, and slope. And it incorporates external sources of information, such as current weather data and even weather forecasts.

Learning Your Lawn

The company is named for the scientific term evapotranspiration, or ET, a measure of the total amount of water released into the atmosphere through evaporation from soil and plants. "In its simplest form, water goes one of three places when you put it in the ground," explains Williams. "Either it evaporates in the air based on sun and wind, it runs off based on the slope and permeability of the soil, or it gets consumed by a plant."

As the system collects more data about your lawn and your climate, ETwater uses machine learning to make smarter predictions about just how much water your plants actually need. The sensors and the sprinkler controller communicate with each other over cellular networks, so there's no need to connect them to your own WiFi network.

In the future, the company plans to release a new mobile app to help people control their water usage from their phones, as well as an open source development kit to help both companies and hobbyists integrate other technologies into ETwater's system.