Plan Reviews

Plan Reviews

A sanitary sewer plan review may be required for new construction, additions or major renovations, relocation or replacement of a sewer lateral, accessory dwelling units (ADUs), outdoor plumbing fixtures, swimming pools, work within or near a sewer easement, sewer main extensions, or other improvements that may affect County-maintained sewer facilities.

The purpose of the review is to verify compliance with applicable Sewer District requirements, identify potential conflicts with existing sewer facilities or easements, determine applicable permits and inspections, and assess applicable sewer fees and charges.

Before You Submit

Applicants are encouraged to review the Sanitary Sewer and Streetlight Requirements Checklist before submitting plans. The checklist identifies information that should be included on the plans and can help reduce review comments and additional review cycles.

Please submit a complete plan set and any supporting information applicable to the project, such as CCTV inspections, survey information, sewer calculations, easement documents, or other requested materials.

Typical Review Times

Our goal is to provide a predictable and timely review process. Typical review times are:

• Major private development – first submittal: approximately 4 weeks 
• All other reviews, including subsequent reviews of major private developments: approximately 3 weeks 

Review times begin when a sufficiently complete submittal is received.

Additional review time may be necessary for unusually complex projects, incomplete submittals, sewer capacity evaluations, easement or legal issues, coordination with other agencies, significant changes to the project scope, or other circumstances requiring additional analysis. Applicants will be notified when additional review time is anticipated.

Resubmittals

For each resubmittal, please provide:

• A complete revised plan set; 
• A written response to each Sewer District comment; 
• The plan sheet or supporting document where each comment was addressed; and 
• Any requested CCTV, survey information, calculations, easement documents, or other supporting information. 

Clearly identify revisions made since the previous submittal. If a comment is not incorporated, provide an explanation and supporting information for Sewer District review.

After Plan Approval

The project designer is responsible for incorporating all Sewer District comments, redlines, and required revisions into the final construction plan set.

The plans used for construction must be consistent with the plans approved by the Sewer District. The final approved plans shall be available to the contractor and Sewer District inspector during construction and inspection.

Sewer District inspectors will inspect the sewer work for consistency with the approved plans and applicable Sewer District requirements. If the construction plans do not incorporate required comments, redlines, or revisions, or if the sewer design is changed after approval, the Sewer District may require revised plans to be submitted for additional review and approval before the affected sewer work proceeds or is accepted.

Plan approval does not authorize construction. Required Sewer Inspection Permits, encroachment permits, building/plumbing permits, and other applicable permits must be obtained before the associated work begins.

Fees

Plan review and other applicable sewer fees and charges are based on the current County fee schedule. Additional fees or charges may apply depending on the project.

If you are unsure whether your project requires a plan review or what information should be submitted, please contact the Sewer District.

Sewer Inspection Permits (SIPs)

Sewer Inspection Permits (SIPs)

A Sewer Inspection Permit (SIP) is required for certain types of construction or modification of sanitary sewer facilities within County-maintained sewer districts.

Before applying, use the County-Maintained Sewer Districts Map to confirm that the property is within a County-maintained sewer district.

Sewer Inspection Permit (SIP) Application Form (Opens in new tab)

Important: Do not submit payment with your application. County staff will review your application, confirm applicable requirements and fees, and provide payment instructions.

Other Permits May Be Required

An SIP covers County Sewer District requirements and inspections. Depending on the type and location of the work, you may also need an Encroachment Permit, Building Permit, or other applicable permits.

For properties within an incorporated city or town, contact the applicable local agency regarding additional permit requirements.

How to Obtain an SIP

1. Complete and Submit the Application

Complete the Sewer Inspection Permit (SIP) Application Form and submit it by email to sewers@smcgov.org or in person at our office located at 555 County Center, 5^th Floor, Redwood City, CA 94063.

If you do not yet have a contractor, you may leave the Contractor section blank and provide the information later.

You may also make an appointment if you would like assistance completing the application or determining what is required for your project.

2. County Review

County staff will review the application to confirm:

• the property is within a County-maintained sewer district; 
• an SIP is required; 
• applicable fees; and 
• any additional information or requirements. 

Depending on the work, additional information such as CCTV footage, approved plans, or other documentation may be required. Staff will contact you if additional information is needed.

3. Pay the Confirmed Fees

Wait until County staff confirms the amount due before making payment.

The base SIP fee is currently $300. Additional fees may apply depending on the project.

After receiving payment instructions, payment may be made through the online sewer payment portal or by check payable to County of San Mateo.

4. SIP Issuance

Once applicable requirements are satisfied and required fees are paid, County staff will issue the SIP.

The SIP is valid for one year from the date of issuance. A fee is required to renew an expired SIP.

Do not begin sewer work until the SIP and any other required permits have been issued.

Scheduling Inspections

Depending on the work, more than one sewer inspection may be required.

The permittee must provide the County Sewer District a minimum of two (2) working days' notice when requesting an inspection. Because inspection appointments are limited, we recommend scheduling as early as possible. Same-day inspections are not available.

Schedule your inspection using the link or QR code on your SIP, or contact the Sewer Division at (650) 599-1403.

When scheduling, provide your:

• name and phone number; 
• property address; 
• SIP number; and 
• requested inspection date and time. 

Someone familiar with the sewer work must be present on-site for the inspection. The issued SIP and applicable approved plans, Standard Provisions, and Standard Details must be available on-site.

SIP Closeout

After all required sewer work and inspections are complete, County staff will verify that applicable closeout requirements have been satisfied.

If additional documentation, corrective work, or fees are required, staff will contact the applicant. Once all requirements are met, the County will close out the SIP and complete any associated County sewer signoff.

A copy of the closed SIP is available upon request.

Questions and Assistance

Need help? We recommend making an appointment with Sewer Division staff. Staff can help confirm sewer district jurisdiction, determine whether an SIP is needed, and answer questions about your project and the application process.

• Email: sewers@smcgov.org
• Phone (voicemail): (650) 599-1403
• Make an Appointment

Annexations & Mainline Extensions

Annexations & Mainline Extensions

If your property isn’t currently part of a county maintained sewer district, it may be possible to join via annexation or mainline extension.

This is only possible in limited areas, and only under very specific conditions.

Please contact us for more information about annexation and mainline extensions.