Pull two statements with matching fields

You need the current bill and at least one prior bill (previous cycle or same month last year). From each, capture:

• Service start/end dates (days in period)
• Usage in the utility’s unit (CCF, gallons, etc.)
• Water $, sewer $, fixed fees, and total $
• Any “estimated read” flags

If the paper bill is thin, the utility portal’s usage graph is often better than the PDF for daily patterns.

Normalize to units (or gallons) per day

Compute usage ÷ days for each period. A 35-day cycle will look “high” in total units even when daily use is normal. Comparing totals without day counts is the most common self-own in bill arguments.

Educational only: convert CCF to gallons with ×748 if you want a household-scale picture.

Have both bills in hand? The two-bill spike splitter splits the difference into billing days, usage per day, rate or tier, sewer and fees.

Build the four-box diagnosis

Units/day up, $ up → usage story (leak, irrigation, guests, pool).
Units/day flat, $ up → price story (rates, tiers, fees, sewer rules).
Units/day down, $ up → rate/fee shock or sewer recalculation.
Units/day up, $ flat → credits, caps, or bill composition quirks — verify line items.

This decides whether you dye-test toilets tonight or read the rate PDF first.

Check tiers and sewer before blaming fixtures

If dollars rose faster than units, highlight tier thresholds and sewer method (volumetric, winter average, cap, flat). A one-unit tier jump can matter more than a short shower experiment.

Turn the comparison into one experiment

Pick the branch the four-box points to. Prove it with a meter baseline and a 3–5 day change — or decode the PDF for a ranked list. Avoid changing five habits at once; you will not know what worked.