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Tankless Water Heaters in Sacramento: Cost, Sizing and Hard Water

A tankless water heater heats water only while a tap is open, so there is no tank to keep hot. National guides put installed cost at about $1,400 to $5,600 (HomeGuide) or $1,400 to $3,897 (Angi). DOE says gas tankless units can be 24% to 34% more efficient for homes using 41 gallons a day or less. Call (916) 712-7030 for a local quote.

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How does a tankless water heater work?

When you open a hot tap, cold water flows into the unit, a flow sensor detects it, and a gas burner or electric element heats the water to the set temperature as it passes through a heat exchanger. When the tap closes, heating stops. That is how a DOE Building America guide describes it, and it is why tankless units avoid the standby heat loss of a storage tank.

Each unit needs a minimum flow, 0.4 to 0.9 gallons per minute per the DOE guide, before it fires, so a thin trickle may run cold. Because there is no tank to corrode, DOE says tankless water heaters can last more than 20 years, compared with 10 to 15 years for most tanks.

How much does a tankless water heater cost?

HomeGuide's 2026 range is $1,400 to $5,600 installed; Angi's 2026 average is $2,631 within a $1,400 to $3,897 range. Both are national. Converting from a tank costs more than replacing a tankless unit, because the plumber may need to run a larger gas line ($350 to $750 per HomeGuide), add new venting ($500 to $1,500 if none exists) or add an electrical circuit. SMUD does not list a rebate for gas tankless units.

What size tankless water heater do I need?

Tankless units are sized by flow rate in gallons per minute (gpm) at a given temperature rise, not by gallons stored. The DOE guide's method: add up the flow of the fixtures you might run at once, then find how many degrees the unit must raise the coldest incoming water. Typical flows from the guide are 2.5 gpm for a shower, 2.5 for a kitchen sink, 2.4 to 4.0 for a bathtub and 1.9 for a dishwasher.

In the guide's example, 65°F incoming water heated to 105°F for one 2.0 gpm shower needs a 40°F rise at 2.0 gpm. Two showers plus a kitchen sink would need roughly 7.5 gpm at your required rise. DOE's Energy Saver guide notes that homes using hot water in several places at once may need two or more tankless units.

Is a tankless water heater worth it?

For gas, DOE says tankless units can be 24% to 34% more efficient than storage tanks in homes that use 41 gallons or less of hot water a day, and 8% to 14% more efficient in homes using about 86 gallons a day. For electric, the DOE guide says an electric tankless unit could save about 12% at best compared with an electric tank. Gas tankless units draw a lot of fuel at once, so the in-house gas line usually needs to be 3/4 inch, and the line from the meter may need upsizing.

How hard is the water in Sacramento-area cities?

Hard water is the main maintenance issue for tankless units. Minerals form scale inside the heat exchanger, which restricts flow and can shorten the unit's life, according to the DOE guide. It says manufacturers recommend flushing anywhere from twice a year to once every three years, and some require a water softener when hardness exceeds 8 to 14 grains per gallon (136 to 239 mg/L).

The table below lists total hardness from each local supplier's latest Consumer Confidence Report. Surface water from Folsom Lake and the rivers is soft to moderately hard, while some well water tops 200 mg/L. Sacramento Suburban Water District notes that groundwater tends to be harder than river water, and that hardness can shift through the year as the mix of sources changes.

How do you flush a tankless water heater?

Follow your model's manual. Descaling usually means closing the unit's service valves and circulating the manufacturer's descaling solution through the heat exchanger, then flushing with clean water. If your unit has no service valves, a plumber can add them. HomeGuide puts professional tankless maintenance at $75 to $300 nationally.

Water hardness reported by Sacramento-area suppliers (mg/L as calcium carbonate), from 2025 Consumer Confidence Reports unless noted. USGS scale: 0–60 soft, 61–120 moderately hard, 121–180 hard, over 180 very hard. Values change with season and the mix of wells and surface water.
Supplier or systemTotal hardness (mg/L)Source water in reportReport
City of Sacramento83 system average; 34 American River plant; 63 Sacramento River plant; 15–154 wellsAbout 80% river water, 20% wells2025 CCR
Sacramento Suburban Water District, North Service Area82–240 wells (average 120); 17 purchased surface waterWells plus San Juan surface water2025 CCR
Sacramento Suburban Water District, South Service Area51–280 wells (average 130); 34–63 purchased surface waterWells plus City of Sacramento water2025 CCR
City of Roseville26 Folsom Lake water; 31–280 wells (average 95)Surface water and wells2025 report
Placer County Water Agency, Foothill/Sunset18.6–24.9 (average 21.75)Mostly surface water2025 CCR
El Dorado Irrigation District, Main System10–14 (average 13)Treated surface water2025 report
City of Folsom23–33 (average 26.5)Folsom Lake surface water2025 report
San Juan Water District17Folsom Lake surface water2025 CCR
Citrus Heights Water District100–170 wells (average 137.5); most supply is San Juan surface waterAbout 94% surface water, 6% wells2025 CCR
Fair Oaks Water District48–120 wells (average 84.5); most supply is San Juan surface waterAbout 88% surface water, 12% wells2025 CCR
Carmichael Water District25 river water (fall and winter); 53–210 with wells (average 121)About 70% American River, 30% wells2025 CCR
Sacramento County Water Agency, Central/South47–62 surface water (average 55); 9.1–160 wells (average 44)Surface water blended with wells2025 report
Elk Grove Water District, Service Area 162–240 (average 141)Local wells2025 CCR
Golden State Water, Cordova system25–270 (average 75)Wells and treated surface water2025 CCR
City of Davis61–510 (weighted average 72)Sacramento River surface water plus wells2025 report
City of Woodland58–87 (average 69.4)Sacramento River water, wells as backup2025 report
City of West Sacramento17.1–180 (average 47)Sacramento River2024 CCR (latest posted)
City of Lincoln18.6–24.9 PCWA surface water; 76–100 city wells (average 85)PCWA surface water plus city wells2025 report
California American Water, Antelope75–130 (average 105)Wells plus purchased surface water2025 report

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Frequently asked questions

Does a tankless water heater need a bigger gas line?
Often, yes. A DOE Building America guide says gas tankless units draw large amounts of fuel to heat water quickly, so the in-house line serving the unit usually needs to be 3/4 inch, and the line from the gas meter may need upsizing. HomeGuide puts a larger gas line at $350 to $750 nationally. Ask for this to be priced in the quote.
How often should a tankless water heater be flushed?
Follow the manufacturer. The DOE guide says recommended descaling ranges from twice a year to once every three years depending on the model, use and water quality. With soft lake water, such as El Dorado Irrigation District's 13 mg/L average, you may be at the long end; on harder well water above 200 mg/L, plan on the short end.
What size tankless water heater does a family need?
Size by flow, not family size. Add the gallons per minute of fixtures that run at the same time, such as two 2.5 gpm showers and a 2.5 gpm kitchen sink, and find the temperature rise from your coldest incoming water to about 120°F. Pick a unit rated for that flow at that rise, or plan for two units.

Available across the Sacramento area

Sources

  1. Measure Guideline: Transitioning to a Tankless Water Heater (Building America, 2012) — U.S. Department of Energy / IBACOS
  2. Energy Saver Guide: Tips on Saving Money and Energy in Your Home (2022) — U.S. Department of Energy
  3. How much does water heater installation or replacement cost? (2026) — HomeGuide
  4. How much does water heater repair cost? (2025–2026) — HomeGuide
  5. How Much Does a Tankless Water Heater Cost? [2026 Data] — Angi
  6. Appliance rebates: heat pump water heater (rebate table, program requirements, median installation costs) — SMUD
  7. Hardness of Water — U.S. Geological Survey, Water Science School
  8. Hard Water — Sacramento Suburban Water District
  9. 2025 Consumer Confidence Report — City of Sacramento Department of Utilities
  10. 2025 Consumer Confidence Report (North and South Service Areas) — Sacramento Suburban Water District
  11. 2025 Water Quality Report — City of Roseville Environmental Utilities
  12. 2025 Consumer Confidence Report: Foothill/Sunset system — Placer County Water Agency
  13. 2025 Water Quality Report (Main System) — El Dorado Irrigation District
  14. 2025 Water Quality Report — City of Folsom
  15. 2025 Consumer Confidence Report — San Juan Water District
  16. 2025 Consumer Confidence Report (joint report with San Juan Water District) — Citrus Heights Water District
  17. 2025 Consumer Confidence Report (joint report with San Juan Water District) — Fair Oaks Water District
  18. 2025 Consumer Confidence Report — Carmichael Water District
  19. 2025 Water Quality Report: Central/South Service Area — Sacramento County Water Agency
  20. 2025 Consumer Confidence Report — Elk Grove Water District
  21. Cordova System Consumer Confidence Report (2025 data) — Golden State Water Company
  22. 2025 Water Quality Report — City of Davis
  23. 2025 Annual Water Quality Report — City of Woodland
  24. 2024 Water Quality Consumer Confidence Report — City of West Sacramento
  25. 2025 Water Quality Report — City of Lincoln
  26. 2025 Annual Water Quality Report: Antelope — California American Water
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