The cost to install a secondary water meter for lawn irrigation is determined less by the meter itself than by the water utility’s connection rules, tap fees, backflow requirements, trenching, and restoration. Ask for a written quote that separates utility charges from plumbing and site work. Then compare the total project cost with the sewer charges you would avoid: annual savings equal irrigation gallons billed through the secondary meter multiplied by the sewer rate and any applicable volume charges. A private sub-meter may not qualify for a sewer exemption unless the utility specifically accepts that arrangement.
What a secondary irrigation meter does
A secondary water meter measures water sent to a dedicated lawn irrigation system instead of measuring the entire property. Depending on the arrangement, it may be a utility-owned second service meter or a privately installed sub-meter downstream of the home’s main meter.
The distinction matters. A utility-installed meter may be read and billed directly by the municipality and may qualify automatically for the utility’s irrigation sewer exemption. A private sub-meter may only document usage for a billing adjustment, and some utilities do not accept private readings at all. Confirm the acceptable meter type, ownership, location, sealing, and reading procedure before buying equipment.
Most systems are intended to keep irrigation water out of the sewer calculation because that water is applied outdoors rather than discharged into the sanitary sewer. This is not automatic. The local water utility or sewer billing authority decides whether a second meter, seasonal adjustment, credit, or another method is available.
Cost components to include in the estimate
There is no dependable national installed price because municipal fees and site conditions vary substantially. Request a line-item estimate containing the following categories:
| Cost category | What it may include | What to verify |
|---|---|---|
| Utility or municipal charges | Application, inspection, meter set, account setup, tap, connection, or capacity-related fees | Whether the fee is required for a second meter or only for a new public-side service |
| Meter assembly | Approved meter, meter setter, unions, fittings, box, lid, and tamper protection | Utility-approved size, manufacturer, orientation, and access requirements |
| Pipe-splicing hardware | Branch tee or approved saddle, isolation valves, adapters, and transition fittings | Pipe material, outside diameter, pressure rating, and whether the utility requires a specific connection method |
| Backflow protection | Preventer, shutoff valves, test ports, installation, initial test, and certification | Device type, tester credentials, test frequency, and reporting method |
| Excavation and restoration | Trenching, pavement or concrete removal, bedding, backfill, sod, driveway, or landscape repair | Who restores disturbed public and private areas |
| Design and permit work | Plans, plumbing permit, utility review, locating, and inspection coordination | Whether the utility or a licensed plumber must submit the application |
Small, accessible installations near the existing service line generally cost less than work that requires a long trench, pavement removal, difficult digging, or relocation of existing irrigation controls. If the new branch must cross a driveway, compare conventional excavation with an approved trenchless option. A water main trenchless pull cost comparison can help frame the questions to ask, although an irrigation-meter project may use different equipment and approval procedures.
Pipe-splicing hardware and meter placement
The plumbing connection normally creates a dedicated branch from the property’s water service or from an approved downstream point. The exact splice depends on whether the existing pipe is copper, PVC, CPVC, PEX, polyethylene, galvanized steel, or another material, as well as on pipe size and utility rules.
Common components can include an approved tee or service saddle, a full-port isolation valve, a meter setter or straight meter connection, unions, a second shutoff valve, a meter box, and the transition fittings needed to connect to the irrigation main. Some systems also need pressure regulation, a drain or test arrangement, or a separate valve arrangement required by the backflow assembly. These are design and product decisions, not universal code requirements.
The meter should remain accessible for reading, testing, repair, and replacement. Do not bury unions, test ports, or required shutoffs under permanent landscaping or concrete. Ask the utility for its standard detail before the trench is opened. The utility may require a particular meter setter, box dimensions, service depth, bedding material, or separation from other utilities.
When the new connection is made on the public side of the existing meter or involves the municipal service, the utility may require its own crew or an approved contractor. A plumber should not assume that a private property connection authorizes work in the public right of way. If the project requires replacement or modification of the incoming service, review related site constraints such as those discussed in this guide to replacing a water service line under a driveway.
Municipal water utility tap fees and approvals
Ask the water and sewer utility whether the proposed meter is classified as a second domestic service, irrigation service, private sub-meter, or another category. The classification can change the application process, meter ownership, monthly charges, tap fee, inspection requirements, and sewer-billing treatment.
Possible municipal charges include an application fee, meter or account fee, inspection fee, service connection charge, tap fee, utility construction charge, and recurring minimum charge. Not every project has every fee. A second meter on an existing private service may be handled differently from a new public connection at the property line.
Before signing a plumbing contract, obtain written answers to these questions:
- Does the utility allow a dedicated irrigation meter at this address?
- Must the utility furnish and set the meter, or may the contractor install it?
- Is a new public-side tap required, or can the branch be taken from the existing service?
- What are the one-time fees and recurring monthly charges?
- Is a plumbing permit or utility inspection required?
- Does the sewer authority accept the meter reading for an exemption or credit?
- Who owns the meter, box, valves, and backflow device after installation?
Verify these items with the local authority having jurisdiction, which may be the water department, sewer billing office, building department, or a combination of agencies. A contractor’s estimate is not a substitute for the utility’s written fee schedule and approval.
Backflow preventer inspection and certification
Irrigation systems can create a cross-connection risk because water may contact fertilizer, pesticides, soil, stagnant piping, or other substances. The utility may therefore require a backflow prevention assembly on the irrigation branch. The required assembly and its location depend on the local cross-connection program, system design, elevation, irrigation equipment, and hazard classification.
Backflow protection is not the same as a simple shutoff valve. A testable assembly may have test ports and two shutoff valves, and it must be installed so an authorized tester can access it. Some jurisdictions require an initial test before service is activated and recurring testing afterward. Others may accept a different protective arrangement for a specific installation. These are local requirements, not universal rules for every property.
Ask the utility or building department for the following before installation:
- The approved backflow device type and size
- Whether the device must be above grade, in a heated enclosure, or in another protected location
- Who may install and test it
- Whether the tester must hold a local or state-recognized certification
- How test results are submitted and how often renewal is required
- Who pays for failed tests, repairs, winterization, and replacement
Include the initial test and any required certification in the project budget. Also account for ongoing testing or maintenance if the utility requires it. A low installation quote that excludes the backflow assembly, test, or enclosure may not represent the actual first-year cost.
How to calculate sewer fee savings
The basic savings calculation is:
Annual sewer savings = eligible irrigation gallons × sewer volume rate
If the sewer bill has several volume-based components, use:
Annual savings = eligible irrigation gallons × (sewer volume rate + eligible sewer surcharges)
Do not include water charges unless the secondary meter also changes the water rate. A separate irrigation meter can sometimes add a recurring account or meter charge, so the more useful comparison is net savings:
Net annual savings = avoided sewer charges minus added meter charges and recurring testing costs
Use the utility’s actual billing units. If the bill charges per 1,000 gallons, divide the measured gallons by 1,000 before multiplying by the listed rate. If the utility uses a winter average or seasonal cap, confirm whether irrigation-meter gallons are excluded in the same way.
For a hypothetical example, assume a system uses 12,000 gallons during a billing period, the sewer volume charge is represented by rate R per 1,000 gallons, and the secondary meter has a recurring charge of M for that period. The gross sewer reduction is 12 × R. The net reduction is (12 × R) - M, before any annual backflow testing or maintenance cost. Replace R and M with the figures on the local rate sheet. This example demonstrates the method and is not a typical rate or savings claim.
Also calculate the payback period:
Payback period in years = total installed cost ÷ net annual savings
Use a conservative irrigation estimate based on historical bills, controller records, or measured meter readings. Do not assume every gallon used outdoors qualifies. Some utilities exclude only water recorded by an approved meter, and some offer no sewer credit for residential irrigation at all.
When a secondary meter is financially worthwhile
A second meter tends to make more financial sense when outdoor use is high, the sewer volume rate is substantial, the property has a long irrigation season, and the utility does not charge a large recurring fee for the additional account. It may make less sense when the lawn is small, irrigation use is modest, the sewer bill is capped or based on a winter average, or the required backflow and tap charges are high.
Compare at least two scenarios:
- Keep the existing service: estimate water and sewer charges for expected irrigation use.
- Install the secondary meter: add installation, utility fees, recurring meter charges, testing, and maintenance, then subtract the sewer charges the utility confirms will be removed.
- Check the break-even point: divide the added project cost by expected annual net savings.
Ask the utility for a sample bill or written explanation showing how irrigation-meter usage appears on the account. This can reveal whether the sewer exemption applies to all metered irrigation water, only volume charges, or no portion of the bill.
Contractor quote and approval checklist
Use a written scope that identifies who is responsible for each approval and component. The proposal should state:
- Existing pipe material, size, and connection location
- Meter ownership, model, size, and approved installation method
- Branch tee, saddle, valves, unions, meter setter, box, and transition fittings
- Backflow device, enclosure, initial test, certification, and reporting
- Utility application, tap fee, inspection fee, and account charges
- Trenching, locating, shoring if needed, backfill, and surface restoration
- Permit and inspection responsibilities
- Testing, flushing, startup, and irrigation-system adjustments
- Items excluded from the price, including utility fees and repairs to concealed piping
Do not proceed based only on a verbal promise that the sewer bill will decrease. Keep the utility’s written exemption approval with the contract, and ask when the credit begins. Some billing offices may require the meter to be installed, inspected, registered, and read before an adjustment appears.
Frequently asked questions
Does every secondary irrigation meter eliminate sewer charges?
No. The sewer authority controls its billing rules. Some utilities offer an exemption or credit for approved irrigation meters, while others use a seasonal calculation or do not provide a separate sewer adjustment. Get confirmation from the billing authority before installation.
Is a private irrigation sub-meter the same as a utility meter?
No. A private sub-meter records flow on the property, but the utility may not accept its readings for billing. A utility-approved second meter may have different ownership, sealing, inspection, and account requirements.
Does an irrigation meter still need backflow protection?
Often it does, but the required device and testing schedule vary by jurisdiction and system hazard. Confirm the requirement with the local cross-connection control program and follow the device manufacturer’s installation instructions.
Can a plumber install the meter without contacting the city?
Not necessarily. A private-side branch may still require a plumbing permit, inspection, approved meter, or utility registration. Work involving the public service, right of way, or utility-owned equipment may be restricted to the utility or an approved contractor.