Merrimack County, NH septic permits and regulations

Septic systems in Merrimack County, New Hampshire are permitted by NHDES Subsurface Systems Bureau under Env-Wq 1000.

Septic permit program

  • Program type: State Agency
  • Authorized agent: Merrimack County Health Department
  • Own septic program: No, uses New Hampshire state rules
  • Local rules beyond the state: No
  • Population: 153,808

Permit fee comparison

Average septic permit fee in Merrimack County: $450. New Hampshire average: $450.

Local rules

County operates under state-level Env-Wq 1000 (Subdivision and Individual Sewage Disposal System Design Rules). Contact local health department for any additional county-specific requirements.

What SepticPro has on file for Merrimack County

  • 1 permit fee with sources
  • The agency phone, email and office address
  • Setback distances
  • Soil and perc test requirements
  • Allowed system types
  • System design rules
  • Inspection requirements
  • Maintenance and pumping rules
  • Point-of-sale rules
  • Installer, designer and pumper licensing

Create a free account to see the full details.

Draw a permit-ready site plan for Merrimack County

Enter the address, draw the system on the aerial with the parcel lines and topo, and print it to scale for NHDES Subsurface Systems Bureau. See how SepticPro site plans work.

Other New Hampshire counties

Data checked 2026-03-16. Always confirm requirements with NHDES Subsurface Systems Bureau before applying.