Earlier editions: 2026-09
Title 13 — WATER, SEWERS AND PUBLIC SERVICES
Napa County Municipal Code Ch. 13.44 Septic Tanks
Napa County Municipal Code · 2026-10 edition · updated 2026-10-04 · Napa County
Cite as: Napa County Municipal Code Chapter 13.44 · Text as of 2026-10-04
13.44.010 - Plan submittal—Contents.¶
Plans for all septic tanks shall be submitted to the administrative authority for approval prior to installation. All septic tanks, sumps and grease interceptors shall meet the current International Association of Plumbing and Mechanical Officials (IAPMO) material and property standards for prefabricated septic tanks and must have an IAPMO approval listing.
(Ord. 1109 § 1 (part), 1996)
13.44.020 - Capacity of tanks.¶
The liquid capacity of septic tanks shall conform to Table 13.44.020, as determined by the number of potential bedrooms in dwelling or apartment units, and determined by the number of fixture units in other properties.
Table 13.44.020 Capacity of Septic Tanks
| Dwellings: Number of Bedrooms | Other Properties: Maximum Fixture Units Served | Liquid Capacity in Gallons |
|---|---|---|
| 1 to 4 | 25 | 1,200 |
| 5 or 6 | 33 | 1,500 |
| 7 or 8 | 45 | 2,000 |
| 9 or 10 | 60 | 2,500 |
Note: Tank capacity shall be two hundred fifty gallons per bedroom in excess of the number listed. Septic tank capacity requirements in excess of two thousand five hundred gallons shall be calculated at a rate of thirty gallons for each additional fixture unit in excess of sixty fixture units.
(Ord. 1109 § 1 (part), 1996)
13.44.030 - Watertight tests on septic tanks.¶
The administrative authority may require a twenty-four-hour watertight test on septic tanks, sumps and grease interceptors. These tests shall be conducted as part of the routine inspection on the septic tank and sumps, shall establish that the entire tank is watertight and shall be coordinated with the administrative authority. At the end of the twenty-four-hour period, the administrative authority must verify no significant drop in the water level.
(Ord. 1109 § 1 (part), 1996)
13.44.040 - Risers required when.¶
A. The administrative authority may require watertight risers to be installed to grade on septic tanks, sumps and grease interceptors that are installed in high ground water areas or areas where water infiltration into the tank may be a concern. For the purpose of this subsection watertight risers shall mean sealed to the topmost joint on the riser.
B. When watertight risers are required, the twenty-four-hour watertight test shall include the entire volume of the riser, and shall be completed as per Section 13.44.030.
(Ord. 1109 § 1 (part), 1996)
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