Will a second meter for irrigation cut your sewer bill?

Find how your sewer charge is set

Check your bill or rate page for which of these your utility uses:

• All metered water: sewer is billed on everything through the meter, so lawn water counts. A deduct meter can help here.
• Winter average: Pima County, Arizona sets residential sewer use from the December–February average for the fiscal year that follows, and doesn’t charge sewer on usage above that average. Summer watering may already be off your sewer bill.

SourceMetro Water District (Tucson): Dual Metering FAQ · accessed Oct 10, 2026

Deduct meter vs. charge meter

Seattle Public Utilities describes two kinds of submeter that are physically the same but billed differently. A deductible meter sits on the line that feeds the allowable deduction, and its reading is subtracted from your sewer charges. A chargeable meter sits on a line that does drain to the sewer, and its reading becomes the basis for sewer charges. Most customers are only authorized to install deduct meters, for uses like irrigation.

SourceSeattle Public Utilities: Apply for Sewer Submeters · accessed Oct 10, 2026

Portland Water District in Maine calls the residential version a deductive or subtractive submeter, used for lawns, gardens, and pool filling.

SourcePortland Water District: Submeter Application · accessed Oct 10, 2026

Count every cost, not just the meter

Utilities publish their own fees, and they differ:

• Portland Water District (Maine): the customer bears all installation and maintenance costs. The submeter will carry a $3.25 monthly charge starting January 1, 2027. A troubleshooting visit when the meter can’t be read costs $75, and unused equipment can be returned within 90 days, less a $30 restocking fee.
• Metro Water District (Tucson): an up-front application fee equal to the “Meter Fee” part of its connection fee for a 5/8-inch meter, then a monthly fee of one-third of the 5/8-inch Water Availability Rate, plus your own plumbing to move all outdoor taps onto the new meter. The fee isn’t refunded if you cancel.
• Seattle: customers buy, install, and maintain their own authorized submeters, and pay fees covering inspection, billing setup, and plan review.

SourcesPWD application · Metro Water FAQ · Seattle Public Utilities · accessed Oct 10, 2026

Estimate your outdoor use with the meter you have

Metro Water suggests timing each irrigation zone: read the meter over part of a cycle (for example, 10 minutes of an hour-long cycle, then multiply by 6), multiply by cycles per month, and add all zones and other outdoor uses. It also warns that only the sewer volume charge drops, not the sewer service fee, and that you should check each zone for leaks or overwatering before deciding.

SourceMetro Water District (Tucson): Dual Metering FAQ · accessed Oct 10, 2026

Put that monthly number, your sewer volume rate, and your utility’s fees into the calculator at the top of this page.

Who it tends to pay off for

Metro Water says there’s no general answer. Savings have to cover setup, plumbing, and monthly costs over a period you accept. Recovery is generally harder for low or average outdoor users, and the likeliest candidates have pools, orchards, large lawns, or large gardens. If you can cut outdoor use in the winter averaging months instead, it calls that the simplest way to lower sewer fees.

SourceMetro Water District (Tucson): Dual Metering FAQ · accessed Oct 10, 2026

Get approval before you plumb anything

Seattle warns that installing a submeter doesn’t guarantee acceptance, and asks customers to contact it before installing. Its submeters must register in cubic feet, and gallon meters aren’t allowed. Portland requires a plumbing sketch and the town’s sign-off before activation. Metro Water requires the dual meter within five feet of the existing meter.

SourcesSeattle Public Utilities · PWD application · Metro Water FAQ · accessed Oct 10, 2026

Already billed sewer on water that never reached the drain? See the free dispute and leak-adjustment guide, and ask about one-time credits like a pool-fill sewer credit.