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Great Falls, MT: how summer watering affects your sewer bill

Montana · Last checked November 2026

Winter average, no meter needed

Great Falls sets residential sewer charges from your average water use from December through March.

Key facts

Averaging period
December through March.

Do you need a deduct meter here?

Usually not. Because residential sewer is based on winter water use, summer irrigation does not raise the sewer charge. A deduct meter would add cost without much saving. Keep winter water use low to keep the sewer charge low.

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How it works

Sewer charges are usually based on how much water passes through your water meter, even though lawn and pool water never reaches the sewer. Some utilities let you install a second meter, called a deduct or irrigation meter, so that outdoor water is not billed as sewer. Others already solve it by basing summer sewer charges on winter water use, so no meter is needed.

  1. Check your bill: if sewer is based on a winter average, you already avoid most summer sewer charges.
  2. If not, ask the utility whether it allows a deduct or irrigation meter and what it charges.
  3. Hire a licensed plumber and pull the permit. Many utilities also require a backflow preventer.
  4. Credits usually start only after the utility inspects and registers the meter, never retroactively.

What it costs

Installation by a licensed plumber often runs several hundred to over a thousand dollars, plus any utility fees. Use the calculator below to see how fast it pays back.

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Sources

Last checked November 2026. Programs open, close and change funding every year. Confirm with the city before you hire anyone. Report a change.