SOLON CONSULTING, LLC.

Business and technical consulting

Talk to Solon

Wastewater Surcharge Calculator

This wastewater surcharge calculator turns discharge volume and strength into the surcharge line your municipality is billing, or is about to start billing. Your local treatment works sets surcharges in its sewer use ordinance and user-charge system to recover what strong waste costs to treat. Under the EPA National Pretreatment Program, those local programs watch breweries, distilleries, wineries, dairies, and food processors. The formula is the same for every industry; only the numbers change.

How to use this tool

Enter monthly discharge volume and the BOD and TSS from a sampling report, then replace the threshold and rate defaults with the values in your own sewer use ordinance. The estimator returns excess pounds discharged, the monthly and annual surcharge, and, if you enter target strengths, what pretreatment would save.

From your water bill or discharge meter. Production water minus product packaged and evaporation is a workable estimate.
From a sampling report if you have one. Food and beverage process wastewater commonly runs in the low thousands; a composite sample is the only real number.
Total suspended solids from the same sampling report.
The concentration your POTW treats as normal domestic strength before surcharging. From your sewer use ordinance or permit.
From the same ordinance.
From your ordinance or sewer bill. Rates vary widely by municipality.
From the same schedule.
Enter a target to see what side-streaming, equalization, or a treatment system would save.
Target TSS after screening or DAF.
Estimate only. Surcharge formulas, thresholds, and rates come from your municipality’s sewer use ordinance, and some POTWs also bill flow, pH excursions, or permit fees. Use your ordinance values above and confirm against an actual bill.

How the Wastewater Surcharge Math Works

Municipal surcharge billing follows one standard formula: flow in million gallons, times 8.34, times the concentration above the ordinance threshold, gives pounds of excess load; pounds times the ordinance rate gives dollars. The 8.34 is the weight of a gallon of water in pounds, which converts milligrams per liter into pounds per million gallons.

The estimate is only as good as the sample behind it. Grab samples taken during a kettle dump or yeast dump can read several times higher than a flow-weighted composite, and some ordinances bill on the grab. Knowing how your municipality samples is worth as much as the treatment discussion.

Worked example

A brewery discharging 100,000 gallons per month at 3,000 mg/L BOD against a 300 mg/L threshold sends 2,252 excess pounds of BOD to the sewer. At $0.50 per pound that is $1,126 per month, or about $13,500 per year, before TSS. Side-streaming the high-strength fraction, yeast and trub in a brewery, whey in a dairy, stillage in a distillery, is usually the first and cheapest correction.

Wastewater Surcharge Questions

What actually drives high-strength BOD?

Product and its precursors in the drain: sugars, alcohol, proteins, fats, and solids. Raw product like beer, whey, stillage, and juice can run to five or six figures in mg/L BOD, so a small volume of lost product moves the composite far more than wash-up and rinse water.

Is pretreatment always the answer?

No. The cost ladder starts with side-streaming high-strength waste for haul-off or land application, then equalization and pH control, and only then mechanical treatment such as DAF or biological systems. Many plants never need to climb past the first rung.

My municipality has not surcharged us. Should I care?

Sampling programs usually arrive with growth, a plant upgrade, or a neighbor’s complaint, and they can bill from the first sample. Knowing your numbers before the municipality does is cheap insurance and a better negotiating position.

When the estimate says the sewer bill justifies engineering, our wastewater pretreatment guide walks the options, written for breweries and distilleries but built on the same principles every food and beverage discharger uses, and our water and wastewater practice scopes the fix through operational consulting.