Nancy Dervin The city of St. Helenaâs current water restrictions allow residential accounts 65 gallons of water per person a day, which amounts to a reduction of about 30-43%, while commercial users only must cut back by 10%. The approach in Lake County is âAll customers in the five water systems are being asked to voluntarily conserve water and reduce usage by 20%â and in Marin County âWe are asking all customers, residential and commercial, to save as much water as they can. Our collective goal is 40%.â Healdsburg residential customers were given a water budget of 74 gallons per person per day while their commercial customers must reduce usage by 40%.