The formula (RMC 12.16.555(b)(6)(i)c)
Meals per peak hour × waste flow rate × retention time × storage factor = interceptor liquid capacity.
| Factor | Code values |
|---|---|
| Waste flow rate | With dishwasher 6 gal; without dishwasher 5 gal; single-service kitchen 2 gal; food waste disposer 1 gal |
| Retention time | Dishwasher 2.5 hours; single serving 1.5 hours |
| Storage factor | 0–8 hour operation 1.5; 8–16 hours 2; 16–24 hours 3; single-service kitchen 1.5 |
Worked example
A 60-seat restaurant with a dishwasher, open 14 hours: assume 60 meals per peak hour × 6 gal × 2.5 h × 2 = 1,800 gallons. A 24-hour casino-adjacent diner with the same seats: 60 × 6 × 2.5 × 3 = 2,700 gallons. A single-service coffee shop open 10 hours: 60 × 2 × 1.5 × 2 = 360 — which the 750-gallon minimum rounds up. The floor is the floor.
What else plan review will want
- Written city approval before installation ((i)b) — and Sparks requires a written permit of approval before any pretreatment device operates (SMC 13.39.070)
- Two compartments, outside the building, restrooms excluded
- Screens on connected fixtures; food solids limited to half an inch
- On a change of ownership, proof the existing tank is “properly sized and functioning” is the new owner’s burden
The calculator next door
Once the tank is in, the frequency calculator turns its size and your real meal counts into the interval you will propose for your EC permit.
Opening or taking over a kitchen?
Call before plan review. We will tell you what the city will want to see.
Call (775) 593-8701Plain-English guidance, not legal advice. Reno quotations are from Reno Municipal
Code Title 12, Ch. 12.16, Art. III (Municode version dated Sep 21, 2026, read 2026-10-08), chiefly
Sec. 12.16.555(b), and from City of Reno Environmental Control handouts. Sparks quotations are from
Sparks Municipal Code Title 13; Washoe County from Ordinance No. 1615. Confirm current requirements
with Reno Environmental Control, (775) 334-4230.