Hi Sangjin,

The water usage is estimated by Netro, not accurate value which is impossible without a flow meter. Here is how we estimate the usage:
1. Calculate the watering time T, which is accurate.
2. Based on your sprinkler type, Netro estimated the flow rate R, which is pretty accurate. E.g. around 1.5inch/hour for Spray Head.
3. Get the zone area from your setting: A.
4. Estimate the water usage as T*R*A.

As we can see, the most error could be from the zone area. By default, we use 1000 square feet, but your zone could be way more smaller of larger. So the usages could also be much smaller or large than the real value. To get a more accurate water usages, please update the zone area with accurate value in settings->zones->Area in sqft.

If you think watering is too much, you can adjust smart watering. Please go to settings->zones->select a zone->smart zone and choose your preferred watering mode. You can choose "Eco" mode to reduce watering. You can also choose "customized" mode to adjust watering by providing the preferred moisture level and flow rate of your sprinklers.

Yours,
Netro Support