To find how many gallons a three compartment sink holds, multiply one bowl’s length, width and depth in inches and divide by 231, the number of cubic inches in a US gallon, then multiply by three. An 18 x 18 x 12 in. bowl works out to about 16.8 gallons when filled to the rim, or about 50 gallons for all three bowls.
Shop the equipment in this article: three compartment sinks, commercial sink faucets and two compartment sinks. Freight is included on every order.
The formula
Gallons per bowl = length x width x depth (all in inches) / 231.
Use the bowl size, not the overall size of the sink. Drainboards and the backsplash do not hold water. Product pages usually list the bowl size as three numbers with the depth last. For example, the 3 compartment sink dimensions on our 36 in. drop-in model (DIS-S3C-101410-F) are three 10 x 14 x 10 in. bowls in a 36 x 18.5 in. footprint.
The result is the volume to the rim. Nobody fills a bowl to the rim, and bowl corners are rounded, so the water you actually use is lower. Working out the volume at your real fill line is more useful, as shown below.
Worked numbers for common bowl sizes
These use the bowl sizes on our own product pages. Rim figures are the full bowl; the fill line figures assume water 2 in. below the rim, which is an example, not a rule.
- 10 x 14 x 10 in. bowls (our S3C-101410-NF and the DIS-S3C-101410-F drop-in): about 6.1 gallons per bowl to the rim, 18.2 for the sink. At 8 in. of water, about 4.8 gallons per bowl.
- 14 x 16 x 12 in. bowls (S3C-141612-NF, 47 x 22 in. overall): about 11.6 gallons per bowl, 34.9 for the sink. At 10 in. of water, about 9.7 gallons per bowl.
- 18 x 18 x 12 in. bowls (S3C-181812-NF, 59 x 24 in. overall, and S3C-181812-RL-NF, 90 x 24 in. with two drainboards): about 16.8 gallons per bowl, 50.5 for the sink. At 10 in. of water, about 14 gallons per bowl.
- 24 x 24 x 14 in. bowls (S3C-242414-NF, 78 x 30 in., and S3C-242414-RL-NF, 120 x 30 in.): about 34.9 gallons per bowl, 104.7 for the sink. At 12 in. of water, about 29.9 gallons per bowl.
The drop-in DIS-S3C-101410-F is on backorder at the time of writing; its page shows the current status.
Why the volume matters
Mixing sanitizer
Sanitizer labels give a dose per gallon of water to reach a set strength. If you guess the volume, you guess the strength. Measure the water you actually put in the sanitizing bowl once, mark the fill line, and use that number every time. The FDA Food Code (section 4-501.114) says chemical sanitizers must be used according to the EPA-registered label, and section 4-501.116 says the concentration must be checked with a test kit or other device. Virginia’s adoption, which reproduces these sections, also sets minimum water temperatures for chlorine by strength and pH, 75 F for quaternary ammonium and 68 F for iodine.
Fitting the largest item
Food Code section 4-301.12 says sink compartments must be large enough to fully immerse the largest equipment and utensils. Volume will not tell you that; the bowl length, width and depth will. Measure your largest sheet pan, stock pot or insert against the bowl size before you order.
Hot water and draining
A bigger bowl takes longer to fill and holds more water to keep at the right temperature. The Food Code sets the manual wash water at 110 F or the temperature on the detergent label (section 4-501.19). If you change sinks, tell your plumber the bowl volumes so the water heater and any grease interceptor can be checked against the new load. Sizing those is a local plumbing question.
Your local health department has the final say on how these rules apply to your kitchen.
Quick tips
- Write the fill line volume for each bowl on a label near the sink so every shift doses the same way.
- Keep test strips for your sanitizer at the sink.
- Change the water when it is dirty or the sanitizer reads low, not only at the end of the shift.
- Use a pre-rinse step to keep the wash water cleaner for longer.
What to buy
- A three compartment sink sized to your largest pan. Our S3C models come with 10 x 14, 14 x 16, 18 x 18 and 24 x 24 in. bowls.
- A pre-rinse basket for scraping and rinsing before the wash bowl.
- A faucet that reaches all three bowls, from our commercial sink faucets.
- Sanitizer test strips matched to the chemical you use.
Freight to the 48 contiguous states is included in the price on every product page.