Applied is not bought
At the defaults, 45 gallons of water touch each car and the site buys 25.1 of them. The difference is the loop. Of the 45 applied, 12 has to be fresh — final rinse and anything the equipment will not run reclaimed water through — leaving 33 reclaimable. Recover 65 percent of that and 21.45 gallons come back, less 1.5 gallons of blowdown and pit clean-out, so just under 20 gallons return to service and 25.1 has to be bought.
Every one of those figures is a meter reading rather than a rating. The one that is nearly always taken from a brochure instead is the recovery percentage, and it is the one the whole page turns on.
Which meter the sewer bill reads
Some utilities meter discharge separately and bill sewer on it. Others bill sewer on the water that came in and do not care what leaves. On a car wash that difference is real money, because four gallons a car drive off wet or evaporate and never reach a drain. Under a discharge meter you buy those four gallons once. Under intake billing you pay water and sewer on them both. The bill says which, and it is worth reading before anybody prices a reclaim system on a saving that assumes the wrong one.
Recovery falls in the places nobody logs
Recovery drops when the pits are due for clean-out, and drops again in freezing weather when parts of the loop get isolated. A figure taken in September is not the figure for January. The sweep on the page walks recovery from zero to ninety so you can see the shape: the first half of the range is worth much more than the second, because the fresh-only rinse volume sets a floor that no recovery percentage can get under.
Payback is not the only reason a loop exists
The page gives a simple payback on water and sewer at today rates. Plenty of sites did not install a loop for that reason at all. They installed it because the fresh supply would not carry the flow, or because the sewer connection would not take it, and in that case there was no version of the site without the loop and the payback question does not arise. Both of those are conversations with the utility and the authority that issued the permit, not with a calculator.
Questions people ask
How much water does a car wash use per car?
It depends entirely on the equipment and on whether there is a reclaim loop, which is why every figure on this page is one you meter rather than one it supplies. What the page does is separate the two numbers people confuse: water applied to the vehicle, and fresh water the site has to buy. At the defaults those are 45 gallons and 25.1 gallons, and only the second one appears on a bill.
How do I measure reclaim recovery?
Two meters and a counted period. Gallons returning to the reclaim tank divided by gallons sent to the pits, over a week rather than an hour. A system rating is not a measurement and will normally read high, because recovery falls when the pits need cleaning and falls again in cold weather when parts of the loop are isolated.
Is sewer charged on what I discharge or on what I buy?
Both arrangements are common and the difference is on your bill rather than in any general rule. Where discharge is separately metered, water that leaves on the car or evaporates is bought once and sewered never. Where sewer is billed on metered intake it is charged twice. The page has a switch for it because the choice moves the per-car cost noticeably.
Does a reclaim system pay for itself?
The page gives a simple payback from your own rates, your own recovery and your own running cost, and it will say plainly when there is not one. What it cannot weigh is the reason many loops were installed in the first place, which is that the fresh supply or the sewer connection could not carry the un-reclaimed flow. Where that is true there is no comparison to make.
What are the rules on discharging car wash water?
Not something this page states, and not something it could. Collection, pretreatment and discharge of wash water are permitted and regulated activities decided by your sewer district, your state and the permit the site holds, and they differ by city and change over time. Every number here is a volume or a rate you supplied. Ask the authority that issues the permit.