How Many Hand Washes Can You Get From a Portable Sink Water Tank?

Our portable handwashing stations have 5-gallon freshwater tanks that can provide approximately 30–35 handwashes as a general planning estimate. The actual number of handwashes depends on faucet flow, how long the water runs, and whether the same supply serves other washing activities.

Understanding water consumption can help you estimate refill frequency and determine whether a station can support your operation.

How Do You Calculate Handwashes per Tank?

To estimate the number of handwashes available from a freshwater tank, determine how much water the faucet uses during each wash.

Two calculations can help:

Water used per handwash = Faucet flow rate (gallons per minute) × Water-running time (minutes)

Estimated handwashes = Freshwater tank capacity ÷ Water used per handwash

The following examples illustrate how flow rate and running time affect consumption. Water-running time refers to the total time the faucet is open during each handwash, not necessarily the entire handwashing process.

These are hypothetical calculations, not measured performance figures for our products. They assume the full 5 gallons are usable for handwashing, with no additional water consumption. Actual results may vary.

Does the Number of Sink Basins Affect Water Consumption?

The number of basins does not automatically determine how much water a portable sink uses. Consumption depends on which basins are used and for what activities. For example, our Dual-Basin Portable Hand Sink (Model 35-0202) has two separate basins that share a single 5-gallon freshwater tank.

Our Food Truck Hand Wash Sink – 4 Compartment (Model 35-0090) combines three warewashing basins with a dedicated handwashing basin.

Because all four compartments draw from the onboard freshwater supply, filling the warewashing basins and rinsing utensils reduces the amount available for handwashing.

For combination sinks, estimate total consumption across all washing activities rather than applying the 30–35-handwash figure without adjustment.

How Often Will You Need to Refill a Portable Sink?

Refill frequency depends on the number of handwashes expected during an operating period and the average amount of water used.

Suppose your operation expects 75 handwashes and you use 30 handwashes per tank as a planning estimate.

75 handwashes ÷ 30 handwashes per tank = 2.5 tankloads

Plan for three tankfuls of freshwater in total: one at the start and two refills during operation, assuming actual consumption matches the estimate.

Allow additional freshwater when consumption may exceed the estimated amount.

How Does Wastewater Tank Capacity Affect the Number of Uses?

Our portable handwashing stations collect used water in separate wastewater tanks with at least 15% more capacity than their freshwater tanks. This additional holding space does not increase the amount of clean water available for handwashing.

Before refilling the freshwater supply, check the wastewater level and empty the holding tank if necessary. Dispose of collected wastewater at an approved sanitary disposal location.

How Can You Get a More Accurate Handwash Estimate?

A practical way to determine water consumption is to measure how much freshwater your station uses under normal operating conditions.

To establish an average:

1. Begin with a known water level. Fill the freshwater tank to its intended operating level.
2. Track usage. Count the handwashes completed during a typical operating period.
3. Measure consumption. Record how much water is needed to restore the tank to its starting level.
4. Calculate the average. Divide the gallons consumed by the number of handwashes recorded.

Divide the tank's usable freshwater capacity by the average water consumed per handwash to estimate the number of uses per fill.

For combination sinks, conduct the measurement while only the handwashing basin is being used. This prevents water consumed during warewashing from affecting the estimate.

Do not shorten necessary handwashing procedures to conserve water.

Choose a Portable Handwashing Station for Your Water Needs

Freshwater capacity is one consideration when selecting a portable sink. The basin configuration and intended washing activities also influence how frequently a station will need servicing.

At The USA Trailer Store, we offer portable hand washing stations with freshwater and wastewater tanks in several configurations.

Explore our available models to compare basin options, water-temperature features, and equipment suited to different operating needs.