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Recycled Water for Vineyards in Napa and Sonoma

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

Yes, California law allows recycled water, meaning treated municipal wastewater, to irrigate vineyards, and for vineyards where the water does not touch the grapes the minimum treatment level in Title 22 is undisinfected secondary water (22 CCR 60304(d)). In practice, a North Bay vineyard can only use it where a supplier’s pipeline reaches the parcel, chiefly Napa Sanitation District’s pipelines toward Carneros and Coombsville and Santa Rosa’s and the Sonoma Valley sanitation district’s systems in Sonoma County. For a buyer, a working connection can change how much a vineyard depends on wells.

Water is often the hardest limit on what a vineyard parcel can do. In Napa County’s Milliken-Sarco-Tulucay (MST) area east of the city of Napa, which the county has designated groundwater-deficient, new water use faces strict limits. In Carneros, the Los Carneros Water District says drinking water still comes from private wells and creek diversions it does not control. This guide covers the rules that govern recycled water on a farm, the systems that serve Napa and Sonoma vineyards as of October 2026, and the questions to ask before you buy a parcel that uses it.

What Title 22 allows on a vineyard

California’s recycled water criteria are in Title 22 of the California Code of Regulations, starting at section 60301. Section 60304 ties each irrigation use to a minimum treatment level. The four levels that matter for agricultural land are summarized below.

Treatment level (22 CCR 60304)	Minimum level for	Vineyard relevance
Disinfected tertiary	Food crops where the water contacts the edible portion; residential landscaping; parks, playgrounds and school yards; any irrigation use not otherwise listed	Needed if the irrigation method would wet the fruit, and for the landscaping around a house
Disinfected secondary-2.2	Food crops whose edible portion grows above ground and is not contacted by the water	Above the vineyard minimum
Disinfected secondary-23	Cemeteries, freeway landscaping, restricted-access golf courses, certain pasture and controlled-access nonedible vegetation	Above the vineyard minimum
Undisinfected secondary	Orchards and vineyards where the water does not contact the edible portion, plus fodder, fiber and seed crops	The legal floor for drip or under-vine irrigation that keeps water off the grapes

The regulation sets minimums, not what a supplier actually delivers. Santa Rosa’s regional system, for example, treats its water to tertiary level with ultraviolet disinfection, according to a June 2024 North Coast Regional Water Board staff report. Ask the supplier what level its water meets, because the level decides where on the property the water may go. Section 60304(e) adds that recycled water may not touch the edible portion of food crops eaten raw unless it meets the tertiary standard.

Rules that apply on the ground

Section 60310 sets use-area requirements that shape where pipes, sprinklers and ponds can go on a vineyard estate. The distances are measured from a domestic water supply well.

Tertiary water: no irrigation within 50 feet of a domestic well unless five conditions are met, including a geological showing of a protective aquitard, a sealed and housed wellhead, drainage away from the well and the well owner’s approval. No impoundment within 100 feet.
Disinfected secondary-2.2 or secondary-23 water: no irrigation or impoundment within 100 feet of a domestic well.
Undisinfected secondary water: no irrigation or impoundment within 150 feet.
Spray near homes: for anything other than tertiary water, no spray irrigation within 100 feet of a residence or a place with similar public exposure.
Runoff and spray: runoff must stay in the use area unless the regulator authorizes otherwise, and spray, mist or runoff may not enter dwellings, outdoor eating areas or food handling facilities. That matters for a property with a tasting room or event space.
Signs and plumbing: publicly accessible use areas need signs at least 4 by 8 inches reading “RECYCLED WATER — DO NOT DRINK”; there may be no physical connection to a drinking water system except as the state’s cross-connection rules allow; and piping in public-access areas may not have hose bibs.

On a parcel with a house well, a guest house and vineyard blocks close to both, these setbacks can decide which blocks may take recycled water. Map the wells before you assume every acre can switch.

Who permits recycled water use

Many recycled water programs in California run under a statewide general order. We read its terms in a notice of applicability that the Central Valley Regional Water Board issued to the City of Visalia, since the State Water Board’s own program page returned no content. That notice describes Order WQ 2016-0068-DDW, “Water Reclamation Requirements for Recycled Water Use,” as adopted by the State Water Board on June 7, 2016. As the notice describes it, the order covers all Title 22 uses except groundwater recharge, with each program run by a designated administrator, usually the agency that produces or distributes the water.

The grower’s side is mostly contractual. In that Visalia notice, the administrator required each user to sign a recycled water user agreement and complete training on approved uses before receiving water, and it inspected use areas on a schedule. Local programs differ, so ask the supplier for its user agreement, rules and inspection practice before you rely on a connection.

Recycled water for vineyards in Napa County

Napa Sanitation District (NapaSan) is the main source. On May 2, 2016, the Napa Valley Register reported that NapaSan and its partners had celebrated the completion of almost $50 million in recycled water projects, including extensions toward Coombsville and into Carneros. The paper said the projects would let the district provide 3,700 acre-feet of recycled water a year.

The facts below are dated to their sources; we could not open NapaSan’s own website to confirm current service.

Area	How water is delivered	Published facts	Cost figures we could verify
Carneros (Napa side)	Los Carneros Water District facilitates delivery of NapaSan water to parcels in its recycled water assessment district	Assessment district of 107 agricultural and residential parcels, about 4,127 acres; construction finished July 21, 2016 (district history page). The Register (May 2016) described a 9-mile, $18 million line that about 100 properties could connect to	Final assessment of $110 per acre for about nine years (district page)
Coombsville / MST area	NapaSan pipeline east of Napa, financed partly through a county Community Facilities District formed in December 2012	The Register (May 2016) described a 5-mile, $16 million extension through which the first recycled water ran the full length in December 2015, with about 50 properties able to connect and 700 acre-feet initially	County project page (undated, read October 2026): special tax of up to $2,000 a year for 20 years for a residential parcel with less than an acre of vineyard; recycled water at $1.57 per 1,000 gallons; on-site connections extra

One discrepancy to clear up: Napa County’s MST project page, which carries no date, still says, as we read it in October 2026, that the county will make a final decision on proceeding after weighing contractor bids, property owner commitments and funding. It also refers to a proposed pipeline route.

The Register, by contrast, reported in May 2016 that the Coombsville extension had been completed. We can’t tell from these sources which parcels are connected today, so treat both as dated and confirm the current service area, rates and connection rules with NapaSan directly.

Parcels with one acre or more of vineyard fall in a separate special-tax category; the county asks owners to contact project staff for an estimate.

For context on why the MST pipeline matters, see our Coombsville guide and our page on Napa groundwater rules for vineyards. The Carneros market itself is covered in our Carneros vineyards guide.

Recycled water for vineyards in Sonoma County

Sonoma Water says the facilities of four municipalities and two sanitation districts produce 30,000 to 40,000 acre-feet of recycled water a year, of which about 15,000 acre-feet is reused for urban and agricultural irrigation; the rest is discharged in winter to the Petaluma River, San Pablo Bay or the Russian River system. It is a member of the North Bay Water Reuse Authority.

Santa Rosa Regional Water Reuse System. The Laguna Treatment Plant produces tertiary water with UV disinfection. The North Coast Regional Water Board’s June 2024 staff report says the city’s recycled water irrigates approximately 6,400 acres of agricultural land and public and private urban landscaping, with the remainder going to the Geysers Recharge Project, which generates electricity.
Sonoma Valley County Sanitation District. A December 2014 San Francisco Bay Regional Water Board staff report on the district’s salt and nutrient management plan put recycled water use at 1,100 acre-feet in 2013 and projected 4,100 acre-feet a year by 2035. We could not confirm current volumes or which vineyard areas are connected, so ask Sonoma Water.

Groundwater rules in Sonoma County are covered in our Sonoma County groundwater guide.

How recycled water changes a vineyard’s water risk and value

A reliable recycled water supply can stand in for some groundwater pumping, which matters most where the groundwater rules are tight. It does not replace the whole water picture. Domestic water still needs its own source, and the supply depends on an agreement or assessment district rather than a well you control. Our guide to vineyard water rights explains how surface and groundwater rights differ from contract supplies.

We have not found published sales data that isolates a price premium for a recycled water connection in Napa or Sonoma, so we don’t quote one. In a valuation, the connection usually shows up as lower water risk and fewer limits on future planting, offset by the special tax or assessment and the water charges. Our page on vineyard valuation explains how water fits into price.

Buyer checklist for a parcel with recycled water

Confirm the connection. Ask for the meter location, the turnout and the date service began. A pipeline in the road is not the same as a connected parcel.
Read the property tax bill. Look for an MST Community Facilities District special tax or a Los Carneros Water District assessment, and how many years remain.
Get the user agreement. Find out who signed it, whether it transfers to a new owner, any annual volume or seasonal limits, and the current rate.
Check the on-site system. Purple pipe, backflow and cross-connection testing records, signs and the irrigation layout should match the supplier’s rules.
Map wells and ponds. Measure the setbacks in section 60310 from every domestic well, and ask whether any pond stores recycled water.
Ask for water quality data. Request recent reports from the supplier, including salinity, and discuss them with your vineyard manager.
Plan for the house. Landscaping around a residence needs tertiary water, and drinking water still needs a well or other source.

Add these items to the broader review in our vineyard due diligence guide, and check storage and distribution against our page on vineyard ponds and reservoirs. Diamond may refer you to partners we work with, such as irrigation designers or vineyard managers; you’re free to choose any provider.

Selling a vineyard that uses recycled water

Buyers will ask the questions above, so answer them in the marketing package: the user agreement, recent bills, the special tax or assessment schedule, a map of the recycled water system and wells, and any inspection or cross-connection reports. A clear file shortens the buyer’s review. Our guide to selling a vineyard covers the rest of the preparation.

This is general information, not legal advice; a California water attorney, together with the supplying agency, should confirm the treatment level, setbacks and transfer terms that apply to a specific parcel.

Questions people ask

Can vineyards be irrigated with recycled water in California?

Yes. Title 22 allows it, and for vineyards where the water does not contact the grapes the minimum treatment level is undisinfected secondary (22 CCR 60304(d)). Suppliers often deliver water treated to a higher level, and the supplier’s rules also apply.

Does recycled water have to stay off the grapes?

Only lower-treated water does. Water that contacts the edible portion of a food crop must be disinfected tertiary under section 60304(a), so the irrigation method and the treatment level have to match.

Which Napa vineyards can get recycled water?

Mainly parcels in the Los Carneros Water District’s recycled water assessment district and parcels near NapaSan’s pipeline in the Coombsville (MST) area. Confirm any specific parcel with NapaSan or the district.

What does recycled water cost in the MST area?

Napa County’s project page lists recycled water at $1.57 per 1,000 gallons and a special tax of up to $2,000 a year for 20 years for a residential parcel with less than an acre of vineyard, plus on-site connection costs. Larger vineyards fall in a separate category.

Does a recycled water connection transfer when I buy the property?

It depends on the user agreement and the district. Assessments and special taxes stay with the parcel, but the agreement itself may need to be reissued in the new owner’s name, so ask the supplier before closing.

How close to a well can recycled water be used?

It depends on the treatment level: 50 feet for tertiary irrigation (with an exception), 100 feet for disinfected secondary, and 150 feet for undisinfected secondary, measured from a domestic water supply well (22 CCR 60310).

If you are weighing a vineyard where water is the open question, we can help you assemble the records and the right questions before you commit. Start with our vineyards and wineries page, or contact Diamond about a specific parcel.

Sources & notes

Last reviewed October 2026 by Matthew Martinez.