Pure Water San Diego is the City of San Diego’s plan to clean recycled water until it can be added to the drinking-water supply. This article explains the pieces of Phase 1, called North City, what each one does, and what the city says about timing.
What is Pure Water San Diego trying to do?
According to the City of San Diego, Pure Water is a phased, multi-year program meant to provide “nearly one-half” of the city’s water supply locally by 2035. The city describes it as the largest integrated infrastructure program it has ever undertaken. It would add a locally produced source to a system that otherwise depends heavily on imported water, a topic covered in where San Diego’s water comes from.
The city’s February 2025 fact sheet lays out two phases:
| Phase | Area | Planned output |
|---|---|---|
| Phase 1 | North City | 30 million gallons per day |
| Phase 2 | Central Area | 53 million gallons per day |
| Total | 83 million gallons per day by 2035 |
The abbreviation “mgd” stands for million gallons per day. The table’s total is simple arithmetic on the city’s figures: 30 plus 53 equals 83. These are design goals set out by the city, not measured deliveries.
Where does the water start?
Pure Water begins with wastewater, which is what leaves homes and businesses through the sewer system. The city says a new Morena Pump Station, planned for the corner of Sherman and Custer streets off Morena Boulevard, just north of Interstate 8, will divert 32 mgd of wastewater to the North City facilities for purification.
From there, two long pipelines are planned. According to the city’s fact sheet, portions of two 10.5-mile pipelines run through Bay Park, Clairemont and University City. One is a 48-inch wastewater line carrying flow north. The other is a 30-inch brine line that carries the byproduct of purification south to the Point Loma Wastewater Treatment Plant. Brine is the concentrated salty leftover that remains after water passes through filtration membranes.
The project also includes tunneling beneath roads and freeways, including at Genesee Avenue and State Route 52, at Genesee Avenue and Rose Canyon, and under Interstate 805. The city says it is adding improved bikeways along several streets within the project limits, including Genesee Avenue, Clairemont Mesa Boulevard, Clairemont Drive and Morena Boulevard.
What does the North City Water Reclamation Plant do?
The North City Water Reclamation Plant already exists, on Eastgate Mall. Today it treats wastewater to what the city calls recycled-water standards, which suit irrigation and industrial uses but are not drinking-water standards. That recycled water is the starting material for Pure Water.
The city is expanding the plant’s capacity from 30 mgd to 52 mgd. By the city’s numbers that is an increase of 22 mgd. The city says the expansion lets the plant keep meeting demand for non-drinking recycled water while also supplying the new purification facility. A new flow equalization basin is part of the work. The city describes it as a way to smooth out peaks in wastewater flow so the treatment processes receive a steadier supply. The city’s project page lists construction as starting in August 2021 with anticipated completion in 2026.
How does recycled water become drinking water?
The new North City Pure Water Facility is being built across the street from the reclamation plant. According to the city, it is designed to produce 30 mgd of purified water meeting state and federal drinking-water standards. It uses a five-step process:
- Ozonation: ozone gas breaks down some contaminants.
- Biological activated carbon filters: filters in which beneficial microbes and carbon remove organic material.
- Membrane filtration: very fine membranes strain out particles and microorganisms.
- Reverse osmosis: water is pushed through a membrane that holds back dissolved salts and many other substances. This step produces the brine mentioned above.
- Ultraviolet disinfection with advanced oxidation: light and an oxidizing process further disinfect and break down remaining compounds.
The city calls this a proven process. Any question about the safety of a particular water supply is ultimately judged by state and federal regulators, whose standards the city says the water will meet. Readers who want the regulatory record should look to those agencies and the city’s own reports.
Why does the water go to a reservoir first?
The purified water does not go straight to taps. The city’s design sends it by pipeline to Miramar Reservoir, where it is stored. From there it is treated again at the Miramar Drinking Water Treatment Plant before distribution to customers, according to the city.
The city’s project page says the pipeline from the purification facility is roughly eight miles long (the fact sheet gives 8.4 miles) and is designed to carry 30 mgd. It follows Miramar Road, runs through Scripps Ranch, tunnels under Interstate 15 and ends at the reservoir. A one-mile branched pipeline was installed on the reservoir lakebed, built on barges and then sunk into place. A dechlorination facility removes disinfectant before the water enters the reservoir, which the city says protects plant and animal habitats and recreational users. Other pieces include improvements at the Miramar Reservoir Pump Station and an automated in-water monitoring system that tracks water quality at the reservoir during construction.
Using a reservoir this way is a design choice. It lets purified water blend with and be stored alongside the reservoir’s existing supply and adds a second round of treatment before delivery.
How do the numbers fit together?
A worked example using only the city’s published figures shows how the parts relate. The Morena Pump Station is designed to divert 32 mgd of wastewater. The purification facility is designed to produce 30 mgd. The difference is 2 mgd, which is consistent with some water being lost as brine and other process streams, though the city’s fact sheet does not itemize that figure, so readers should not treat the gap as an official yield calculation.
Likewise, the expanded reclamation plant’s 52 mgd capacity serves two purposes. If 30 mgd of that flow goes on to purification, about 22 mgd would remain for existing recycled-water customers. That is only an illustration; actual flows will vary with demand, weather and operations, and the city has not published such a split. Readers comparing figures across city documents should also note that capacity, which is what a plant is built to handle, is different from average daily flow, which is what it actually treats on a given day.
What is the status, and what is still unclear?
According to the city’s project pages, the North City Pure Water Facility and Pump Station began construction in April 2021, the pipeline project in June 2021 and the reclamation plant expansion in August 2021. All three pages list anticipated completion as 2026 and describe the projects as under construction. The pipeline page carried construction notices dated as late as October 23, 2026. The city’s project pages do not give a percent complete, a firm opening date, or a total project cost, so those remain unconfirmed here. Startup of a new treatment plant typically involves testing and regulatory sign-off before water is delivered, so “construction complete” and “water delivered” may not be the same date. Earlier city materials gave earlier target dates, which is common for projects of this size, and residents should check the city’s Pure Water pages for the current schedule.
Phase 2, planned for the Central Area, is listed at 53 mgd, but the city’s published materials give little detail on its design or timeline beyond the 2035 target. Because Phase 2 accounts for 53 of the 83 mgd in the full program, most of the long-range goal rests on work that is further from completion than Phase 1. That is worth keeping in mind when reading the “nearly one-half” goal: it describes the finished two-phase program, not what Phase 1 alone would deliver.
How can residents follow construction and have a say?
Because the work runs through neighborhoods, the city posts construction notices and invites residents to sign up for updates. The pipeline page lists nighttime work from 7 p.m. to 5 a.m., Monday through Thursday, along parts of the alignment, and daytime work at the reservoir from 7 a.m. to 4:30 p.m., Monday through Friday, though schedules change. The city also offers a virtual tour of its Pure Water demonstration facility and a program phone line, 619-533-7572.
How the city funds and approves such projects is part of broader municipal decision-making, described in how the city of San Diego builds its budget and how city government is organized.
Phase 1 in brief: a local source still under construction
Phase 1 is a chain of linked projects: a pump station in Bay Park, long pipelines and tunnels, an expanded reclamation plant, a five-step purification facility, and a pipeline to Miramar Reservoir. Each depends on the others, and the city says the chain is designed to deliver 30 mgd. Whether it meets its schedule and output goals will be shown by the city’s own updates and by regulators’ oversight in the months ahead.
This article is general information about a public works program, not an endorsement of the project or personalized advice.
Sources: City of San Diego Public Utilities Department; City of San Diego
