Who Supplies Your Water

2.2.1 Which district serves your address?

The district named on your water bill. Inland North County is split among five retail suppliers, and their lines do not follow community names neatly, so the bill settles it.

Two neighbors round out the area. Rincon del Diablo MWD buys the water for its ID A from the City of Escondido. Vallecitos Water District has taken Carlsbad desalinated seawater since early 2016, about 27% of its yearly supply, per Vallecitos.

2.2.2 Why did Fallbrook and Rainbow leave the Water Authority?

Price, by their own account. FPUD says buying from Eastern gets Metropolitan water "~30% less" than through the Water Authority, and its voters approved the move by 92%. The switch took effect January 1, 2024, for the district's roughly 35,000 residents.

Rainbow followed. Rainbow Water says its detachment became final November 1, 2024, and it paid a first exit-fee installment of $3.2 million. Its 2025 report says Eastern charges the Metropolitan wholesale rate plus a $12 per acre-foot administrative fee.

On the treatment side, both districts receive Metropolitan water treated at the Lake Skinner plant in Riverside County, which is why their hardness sits near 230 mg/L. The details by district are on water hardness by district §2.1.

2.2.3 Where does local water come from?

Mostly from two places: the Santa Margarita River for Fallbrook, and Lake Henshaw for Escondido and Vista. Camp Pendleton wells feed FPUD's Santa Margarita Groundwater Treatment Plant on Alturas Road through a 6.3-mile pipeline. The plant can make up to 7.8 million gallons a day, and Fallbrook homes began receiving its water in late 2021, per FPUD. FPUD now says the river provides about half its supply; its original project target was over 30%.

Escondido treats Lake Henshaw and Lake Wohlford water, plus imported water, at the Escondido-Vista Water Treatment Plant, which can produce up to 75 million gallons a day. VID uses the same plant for its Henshaw share. Valley Center's water comes from Skinner and from the Water Authority's Twin Oaks plant, which blends in Carlsbad desal.

2.2.4 How do you read your district's water quality report?

Start with the source description, then the tables. Every report opens with where the water came from that year; that paragraph explains most of what follows. Then find three rows: hardness, sodium and total dissolved solids, usually in a table of secondary or unregulated constituents.

Each table lists a range and an average by source. Fallbrook's 2026 report, covering 2025, puts hardness at 235 mg/L and converts it to 13.7 grains. Escondido's 2025 report lists sodium at an 88 mg/L average and TDS at 527. Valley Center's report gives Skinner and desal columns side by side with no blended figure. Look also for the disinfectant row: all five districts report chloramine, covered on chloramine and filters §2.4.

2.2.5 Who do you call about what?

Rainbow draws the line at the meter, at least for pressure: the customer installs and maintains the pressure reducing valve on their side of the meter, and the district's own regulators "protect the meter," not the home, per its regulator FAQ.

Who handles what

Your district

Water quality questions, the meter and meter box, billing and leak adjustments, and backflow programs. FPUD and Valley Center test devices themselves; Escondido has owners hire a certified tester.

A licensed plumber

Anything on the house side beyond homeowner tasks: regulator replacement, main-line and repipe work, and repairs after a failed backflow test, which go to a certified technician under your district's rules.

San Diego County

Private well permits and septic systems in unincorporated areas such as Fallbrook, Bonsall, Rainbow and Valley Center.

For leaks, start at the meter yourself: FPUD's leak check has you read the meter, wait 15 minutes and read again with everything off. The full method is on reading your water meter §4.1, and backflow rules by district are on backflow testing §5.1.

2.2.6 Common questions

Q. Did Fallbrook's water change after the switch to Eastern?

FPUD's imported supply is Metropolitan water treated at Lake Skinner, bought now from Eastern. FPUD describes the change as one of seller and price: about 30% less for the same Metropolitan water.

Q. Is Rainbow water still Water Authority water?

No. Since November 1, 2024, Rainbow receives its water from Eastern Municipal Water District, which charges the Metropolitan rate plus $12 per acre-foot.

Q. How much of Fallbrook's water is local?

FPUD says the Santa Margarita River now provides about half its supply, plus about 1% from the Capra Well. The original project target was over 30%.

Q. Why do Escondido and Vista share a treatment plant?

Both draw on Lake Henshaw, and the Escondido-Vista Water Treatment Plant treats that local water along with imported water. It can produce up to 75 million gallons a day.

Q. Does Valley Center get desalinated water?

Part of it can. Valley Center MWD receives water from the Water Authority's Twin Oaks plant, which blends in Carlsbad desalinated seawater, alongside Metropolitan water from Skinner.

Q. Where is Fallbrook's local river water treated?

At FPUD's Santa Margarita Groundwater Treatment Plant on Alturas Road, which can produce up to 7.8 million gallons a day. FPUD's 2026 report says deliveries from the plant began in December 2021.

2.2.7 Sources for this section