Residential rates are designed to cover the actual cost of service. Each residential unit is charged the basic flat rate, $927 as of July 1, 2019. This applies to single-family homes, apartments, condominiums and other multi-family dwellings, and mobile home and trailer parks. For rooming houses, the basic flat rate is applied to each of the first two rooms used for renting and one-quarter of the basic rate for each additional rented room.
For purposes of rates, motels are considered residential. Each motel unit with a kitchen is charged the basic rate, and each motel unit without a kitchen is charged one-half the basic rate.
Non-residential rates are structured individually for each type of non-residential use. To determine an estimated cost to collect and treat wastewater from a non-residential customer, the District calculates the cost based on water usage and a strength factor, which is an average cost to treat wastewater from a particular type of non-residential customer. Thus, a low water user would pay less than a high water user in the same category of non-residential customers with the same strength factor. And, for two non-residential customers with the same water use, the one with the higher strength factor would pay more.
For calculating the non-residential rate, the District obtains an average of winter and summer water usage for each non-residential customer from the Marin Municipal Water District. Excluded is water used solely for irrigation and recycled water that does not enter the District’s sewer system, i.e. water not used for toilet flushing, laundry, commercial car washes, etc.
The average water usage is converted into sanitary units. Each 16 hundred cubic feet (11,968 gallons) of water is equal to one sanitary unit.
A strength factor is applied to each non-residential customer based on the type of use. Users such as office buildings, retail, churches, halls, public agencies, laundromats, service stations, medical offices, barber and beauty shops, car washes, convalescent hospitals, hospitals and the like are given a strength factor is 1.0. High strength users, such as restaurants/cafes, bakeries, mortuaries, hotels with restaurants, and markets with disposals, have a strength factors ranging from 2.4 to 3.2. Mixed uses with low and high strengths are given a 2.0 strength factor. The strength factor is not applied to residences or schools.
The non-residential rate is determined by multiplying the number of sanitary units by the strength factor, and by the basic residential rate.
For example: A restaurant that has an average winter and summer water usage of 40 hundred cubic feet of water would have 2.5 sanitary units times 2.4 for its strength factor which equals 6 sanitary units, times the current residential rate of $927* per year for a total of $5,562.00 a year or $463.50 a month. (*2019/2020 rate)
For information on the specific rates for individual non-residential customers, contact the District office at (415) 472-1734.