Sewer Averaging

Like many other cities Silverton does not meter the wastewater you discharge, and instead uses a sewer averaging period. The assumption for wastewater use is that during the winter months of November through April water usage is primarily inside your residence and which is treated at the Wastewater Treatment Plant.

The sewer charge has two components: (1) Base Charge-$25.84 per dwelling unit and (2) Usage Charge based on water consumption. The sewer usage charge is determined by taking the average monthly water consumption, measured in cubic feet (cf), for a six month period between November (starting after the water meter reading toward the end of October) through April (ending with the water meter reading toward the end of April) billing periods.  Once that average is determined the usage portion of the sewer is bill $7.17 per 100cf of usage (to compare water usage is billed $3.11 per 100cf).  

Unless there is a rate change (link to current rates) which normally occurs in July, this is your fixed sewer rate until the following May when the average is recalculated.  This means the sewer portion of a customer’s bill will not increase in the summer months due to irrigating, car washing, filling of swimming pools or any other outdoor water use.

Residential customers have the option to “opt-out” of the averaging method and have the sewer usage charge based on actual water consumption for each month all year long. To “opt-out” or “opt back in” the customer must complete an “Opt-Out/In” form and submit it to the Finance Department by April 30th. Opt-Out/In’s can only be changed one time per year in April.

All new and existing residential customers who don’t have at least four month of usage for the averaging period will have their sewer charge based on actual usage up to the maximum amount of $81.77 per month (based on 1.5 times the city wide average water consumption of 520cf-updated annually). Customers will see their new sewer average on the May billing.