Monterey Peninsula ADU Water Credits and Permits (2026)

On most of the Monterey Peninsula, an ADU needs water before it can get a building permit. If your home is inside the Monterey Peninsula Water Management District (MPWMD), an ADU that adds plumbing fixtures needs an MPWMD Water Permit, and the water for those fixtures has to come from credits already documented on your property or from a source your city or county releases to the project. On many Peninsula parcels, water is a bigger hurdle than zoning.

The short version: MPWMD measures your ADU’s new fixtures in “fixture units,” and that demand has to be covered before the building permit issues. New Cal-Am meters are still barred by a State Water Board order, so an ADU on a Cal-Am parcel is planned around the main home’s existing connection. A hearing on lifting that ban is underway, with no decision as of November 2, 2026. Water is one of the first things we check on a Peninsula parcel.

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Who this applies to

According to the district, MPWMD serves about 114,000 people in Carmel-by-the-Sea, Del Rey Oaks, Monterey, Pacific Grove, Seaside, Sand City and the Monterey Peninsula Airport District, plus parts of unincorporated Monterey County including Pebble Beach, Carmel Highlands and Carmel Valley.

• Your water company matters. The new-meter moratorium covers California American Water (Cal-Am) connections, and some parcels in the district are on other systems or private wells.
• Not every nearby city is in the district. Marina is served by Marina Coast Water District, and Salinas is outside MPWMD too.

For the city side of the permit, see our Monterey ADU permit guide, our Carmel ADU permit guide, our Pacific Grove ADU page or our Seaside ADU page.

What an MPWMD Water Permit is and when an ADU needs one

Under MPWMD’s water permit rules, a Water Permit is what lets you obtain a building permit and set a meter or intensify water use on an existing connection, and ADUs are on the district’s list of projects that need one. The City of Monterey’s ADU checklist is direct: if plumbing fixtures increase or move, you need an MPWMD waiver or permit, so confirm your water credits before submitting.

How the process runs, per the district’s June 2026 fact sheet, application form and rules:

1. Count the fixtures. The application lists every fixture on the property before and after the project.
2. Get the jurisdiction’s signature. Your city or county signs the water release, which records where the water comes from. Unsigned applications are rejected.
3. Submit plans and pay. Plans go to the district electronically. The initial application fee is $250, capacity fees are based on the fixture units you add, and all fees are due before the permit issues.
4. Record the deed restriction. Under MPWMD Rule 23, every Water Permit includes a “Provide Public Access to Water Use Data” deed restriction, and some projects need others. Deed restrictions need the owners’ notarized signatures.
5. Pass the district’s final inspection, in addition to the building department’s.

Fixture units and water credits, explained

A fixture unit is MPWMD’s yardstick for water demand. Each fixture carries a value, and your permit covers the increase in the property’s total. The district’s ADU guidance says the number an ADU needs depends on what fixtures already exist in the space and what the ADU adds.

Values from MPWMD’s current residential application:

A simple one-bath ADU with a washbasin, a 1.28 gallon toilet, a shower, a kitchen sink with a high-efficiency dishwasher and a high-efficiency washer adds up to 6.8 fixture units by those values. That is only an illustration; MPWMD makes the official count from your plans.

Water credits are how a property earns room for new fixtures. MPWMD documents credits when water-efficient appliances replace older ones or when fixtures are permanently removed, including when a building is demolished. Under Rule 25.5, water use credits last ten years. Three practical rules:

• Keep original fixtures until MPWMD inspects. Credit applications are inspected before permitting, and the district asks that originals stay in place until then.
• Watch January 1, 2027. The district’s credit for installing a high-efficiency (1.28 gallon) toilet expires that day, and the credit for a 0.8 gallon toilet drops from 1.0 to 0.5 fixture units.
• Required retrofits earn no credit. That applies to any retrofit MPWMD requires as a permit condition.

If your credits fall short, the water has to come from a source your jurisdiction controls, such as the public credits, entitlements and allocations listed on the release form. That is the city or county’s call, confirmed parcel by parcel. The City of Monterey, for example, says it has no water credits available for allocation, so an ADU there has to fit within the credits tied to the site (City of Monterey water availability).

One common mix-up: MPWMD’s second bathroom protocol, which lets an older home add a second bath without water from the city or county, cannot be used to create an ADU or JADU.

The new-meter moratorium and the 2026 State Water Board hearing

The State Water Board’s orders against Cal-Am over Carmel River pumping, WR 2009-0060 and WR 2016-0016, include a moratorium on new service connections (Condition 2 of the 2009 order). That is why a new Cal-Am meter is off the table for now.

In October 2025, MPWMD applied to modify those orders, asking the Board to rescind the prohibition on new meters, keep reporting in place, and add supply and demand triggers. Under the proposed trigger, the moratorium would be reimposed immediately if Cal-Am reports diversions above 3,376 acre-feet in any water year under its Order 95-10 rights.

The hearing is on the written record, with a public comment day on November 5, 2026, and closing briefs due November 10. As of November 2, 2026, no decision has been made. Either way, the hearing is about new connections, not the district’s Water Permit process, so fixture units will still matter. We will update this guide when the Board rules.

Shared meter, separate meter or submeter?

MPWMD Rule 23 requires a water company meter for each residential user, with an exception: one ADU on a site may be permanently submetered when the city or county confirms it cannot be split onto a separate lot. An ADU inside the existing space of a home or accessory structure is exempt from submetering, and selling an ADU separately requires its own meter. The City of Monterey’s checklist lets ADU water service branch off the main line just past the meter, as long as it is “meter ready.”

State law adds limits in Government Code section 66311.5. An ADU is not a new residential use for connection fees or capacity charges unless it is built along with a new single-family home. An ADU created within existing space generally cannot be required to take a new or separate connection, unless it is built with a new single-family home or sold separately. For a new detached ADU, a provider may require a separate connection, with a fee proportionate to the unit’s size or drainage fixture units. Our separate utility meter guide covers the billing side.

Water-efficient fixtures every new ADU needs

MPWMD requires a new dwelling to have water-efficient appliances, including the clothes washer, dishwasher and an instant-access hot water system. Adding a bathroom also triggers retrofits across the whole property, main house included.

On a Peninsula project, the district’s flow rates and its instant-access hot water requirement go into the fixture schedule during design, and we confirm them with the district before your home is built in our Salinas factory.

How we handle water on Peninsula projects

We check water first. On a Peninsula parcel, the water questions belong in the feasibility study’s utility review: who serves the property, the existing fixture count, any documented credits, whether the jurisdiction can release water, and the retrofits the main house will need. We confirm water with the district and your city or county before we call it available for your parcel.

Smaller homes need fewer fixture units. Nine of our 14 models have one bathroom, starting with the 450 square foot Four Fifty studio at $199,000. A second bathroom adds about 4.3 fixture units (washbasin, toilet and shower), so the floor plan is often where the water math gets solved.

The paperwork is ours. Our team prepares the fixture count, coordinates the release with your city or county, and files the Water Permit with the building permit. You sign the deed restriction before a notary. Your home is built about 97% complete in our Salinas factory, done-for-you from permits to appliances.

One project price. A permitting budget is built into our all-inclusive pricing. Water permit fees and main-house retrofits are property-specific, so they are confirmed in your feasibility study. Local numbers are in our ADU cost in Monterey guide. Want the water answer for your address? Book a free Online Property Analysis and our team will walk you through it.

Frequently asked questions

Do I need water credits to build an ADU in Monterey or Pacific Grove?

You need enough water to cover the fixture units your ADU adds. Both cities are inside MPWMD, so the ADU needs a Water Permit. The City of Monterey says it has no water credits to allocate, so ADUs there rely on credits documented on the property. In Pacific Grove, ask the city whether any water can be released for your project.

Can I get a new water meter for an ADU on the Peninsula?

Not a new Cal-Am meter while the State Water Board’s moratorium stands. MPWMD Rule 23 allows one ADU to be permanently submetered when the city or county confirms the unit cannot be split off.

What is a fixture unit?

It is MPWMD’s measure of water demand: 1.0 for a washbasin, 1.3 for a 1.28 gallon toilet and 2.0 for a standard shower, for example. Your Water Permit covers the increase in the property’s total.

How long does an MPWMD water permit take?

MPWMD says Water Permits are normally processed within a week, and deed restrictions take 1 to 3 days to prepare, review and record. Permits that use high-efficiency appliance credits need their own deed restriction and may take five to seven business days. Your city or county signs the water release before you apply.

Is the moratorium on new water meters being lifted?

Not yet. MPWMD asked the State Water Board to lift it in October 2025. A public comment day is set for November 5, 2026, closing briefs are due November 10, and no decision had been made as of November 2, 2026.