Mobile detailing water tank planner

How much water should a detailing tank hold?

Multiply your measured water use per job by the number of jobs between refills. Add a reserve for other uses. Compare that amount with the capacity of the tank you are considering. A larger tank also means a larger possible load when full.

Tank sizes and full weight

Water weighs about 8.34 pounds per US gallon, so a full tank is heavy before you add the tank or anything else. The job columns use example water use, not a typical figure. Measure your own use per job and enter it in the planner.

The weights cover water only. Add the empty tank weight from the listing, plus mounts, pump, hoses, and everything else you carry.

The calculation

• Water needed = gallons per job × jobs between refills + reserve.
• Planned fill = the smaller of water needed and tank capacity.
• Water weight = US gallons × approximately 8.34 pounds.
• Added load = water weight + empty tank weight + other load.
• Remaining payload = your entered payload capacity − added load.

The planner shows a shortage when the tank cannot hold the water needed. It compares the weight of a full tank and your planned fill separately. Missing weights stay unknown. Enter 0 only when you mean zero.

Worked example

These are example inputs, not measured operating results or an equipment recommendation. At 18.5 gallons per job, three jobs and a 10-gallon reserve need 65.5 gallons. A 75-gallon tank has 9.5 gallons of unused capacity.

The water weighs about 546.3 pounds at the planned fill, or 625.5 pounds when full. Add a 28-pound empty tank and 620 pounds of other load: the totals become 1,194.3 and 1,273.5 pounds. Against an entered 1,500-pound payload figure, that leaves 305.7 and 226.5 pounds respectively.

With a 60-gallon tank, the same plan is 5.5 gallons short. After the reserve, that tank holds enough water for two whole jobs at 18.5 gallons each. The planned fill is capped at 60 gallons.

Use the right vehicle figure

Payload is the combined weight of occupants and cargo. Gross vehicle weight rating (GVWR) includes the vehicle itself, so do not enter GVWR as payload. Check your exact vehicle's tire and loading label and owner manual. Include added equipment in other load. Count each item once.

A remaining allowance is only a comparison with the number you entered. Check total vehicle weight, axle and tire ratings, load distribution, tank mounting, and the equipment instructions separately. This tool does not approve an installation or model water movement.

Sources and limits

The U.S. Geological Survey gives 8.34 pounds per gallon. Its water density reference explains that temperature and dissolved substances change the weight. Treat the conversion as a planning approximation.

Ford's payload guidance explains the occupants-and-cargo label and how added equipment affects payload. It is a reference for the method; use the instructions for your own vehicle. Sources reviewed September 11, 2026.

Plan water supply and wash-water handling first. Shop for equipment second. Continue with the mobile setup guide, build an equipment list, or price the service. If the setup also runs a pressure washer or vacuum, check its power with the power planner.

Before you buy a water tank

Run the planner first, so you know the size you need and the weight you can carry. Then check each listing for these points.

• Fit: measure the floor space in your truck bed, van, or trailer. Leave room for straps and to reach the lid and outlet.
• Full weight: use the table above, add the empty tank weight from the listing, and compare the total with your payload in the planner.
• Mounting: follow the tank maker's mounting and tie-down instructions. Never carry a full tank unsecured.
• Baffles: ask whether the tank is made for vehicle use and has baffles. Baffles reduce water surging when you brake, turn, and drive.
• Outlet and fittings: match the outlet size and thread type to your pump or pressure washer hose before you order.
• Water feed: read your pressure washer manual for its inlet water supply requirement before you plan to feed it by gravity from a tank. Some setups add a 12-volt transfer pump; see the pump comparison below. The pressure washer comparison lists what the makers of 9 models ask for.
• Drain: a low drain makes the tank easy to empty, including before a freeze. For freeze care of your other equipment, see the winter detailing guide.

Search tanks by size

As an Amazon Associate I earn from qualifying purchases. Details. These are searches, not recommendations. Check each listing against the list above.

• Search 35-gallon tanks on Amazon
• Search 65-gallon tanks on Amazon
• Search 100-gallon tanks on Amazon

Water tanks for mobile detailing, compared

Here are 6 tanks from 60 to 100 gallons. Four are sold as detailing tanks. The two Norwesco tanks are general water tanks, and one seller lists the 68-gallon tank with its detailing tanks. Each row shows only what its listing states. Full weight is the water at 8.34 pounds per gallon, as in the table above, plus the tank weight the listing gives. Mounts, pump, and hoses are extra.

How to use the comparison

• Height: the low tanks stand 16 to 18 inches tall. The leg tank and the 100-gallon tank stand 25 to 26 inches. Measure the space under a bed cover or van shelf first.
• Weight: three listings give no tank weight. Ask the seller, then enter it as the empty tank weight in the planner.
• Baffles: none of these listings says the tank has internal baffles. One seller says the Norwesco leg tank's legs act as baffles. If baffles matter for your vehicle, ask the seller before you order.
• Fittings: outlet sizes and thread types differ, and one listing says fittings are not included. Match them to your pump or pressure washer hose.

As an Amazon Associate I earn from qualifying purchases. Details. The Amazon links are searches for each model name, not reviewed listings, and results can show other tanks. Each tank name links to the listing these figures come from, read October 19, 2026. We have not tested these tanks. Prices and stock change, so check the listing before you buy.

12-volt water pumps for a detailing tank, compared

Most electric pressure washers in our pressure washer comparison ask for a pressurized water supply, not a gravity feed from a tank. A 12-volt diaphragm pump between the tank and the washer can supply it. Here are 9 pumps from 5 makers. Every figure comes from the maker's own data sheet, product page, or manual. Flow drops as pressure rises, so the table shows the maker's flow at 40 psi next to the open flow.

At 40 psi, the 6 pumps with their own published flow table give 1.2 GPM to 4.2 GPM. 3 of them give at least 2.0 GPM there, the supply the Kärcher manuals and the Active 2.0 manual ask for: SHURflo Pro Washdown Kit II Ultimate 5.0, Remco Aquajet 55, variable speed, and Everflo EF5500. 2 give more than 3.0 GPM at 40 psi: SHURflo Pro Washdown Kit II Ultimate 5.0 and Everflo EF5500. The Active 2.0 FAQ asks for 3 GPM at over 40 psi, and flow keeps falling as pressure rises, so check the maker's flow table at the pressure your washer needs. The AR Blue Clean FAQ asks for 5.0 GPM for most of its home machines, or about twice the washer's maximum flow. None of the charted pumps reach 5.0 GPM at 40 psi. The SEAFLO 42 series (long body) and SEAFLO 55 series have no flow table. The 40 psi figure for the Delavan SilverBack 5.0 comes from a table for a whole pump series, so it is not counted.

How to use the pump comparison

• Flow: compare the flow at 40 psi, not the open flow, with the supply your pressure washer manual asks for. Open flow is measured with nothing on the outlet.
• Power: these pumps run on 12 volts DC from a battery, so they are not part of the 120-volt power planner. Use the fuse size the maker gives. Battery size is not checked here.
• Duty: intermittent pumps are not made to run without breaks. SHURflo says not to run its two washdown pumps continuously for more than 20 minutes in an hour, and that the real limit depends on amp draw and heat.
• Switch: every maker sells these as demand pumps, which stop when the outlet closes.
• Hose: the SEAFLO 33 and SHURflo 4008 manuals ask for inlet plumbing of at least 1/2 inch inside diameter. SHURflo's washdown manuals say a standard garden hose is not suitable on the inlet, because it can collapse. Match the port threads to your tank outlet and washer hose.

No pump maker here says its pump is made to feed a pressure washer. Check your washer manual, and test the setup with water before a job. As an Amazon Associate I earn from qualifying purchases. Details. The Amazon links are searches for each model name, not reviewed listings. Each pump name links to the maker's data sheet or product page. Some figures, such as fuse sizes and duty, come from the same maker's manual or brochure. All were read October 22, 2026. We have not tested these pumps.

Which water tank fits your truck bed?

Choose your truck and bed to see which of the compared tanks can sit flat on the bed floor between the wheel wells, how much floor is left, and whether the tank top rises above the bed sides. Bed sizes come from each truck maker's own published specs. If your truck is not listed, measure the bed and enter your own numbers.

Truck bed sizes and the compared tanks

All 16 beds below have room for every checked tank flat between the wheel wells. The three low tanks, 16 to 18 in tall, fit and sit at or below the sides on all 14 beds with a listed side height. The two taller tanks, 25 to 26 in, rise above the sides on all 14. The tightest fit is the 2026 Ford Maverick: 42.6 in between the wheel wells leaves 0.6 in to spare for a tank set with its long side across the bed, so measure your own bed first.

How the fit check works

• Footprint: a tank fits when its length and width fit inside the bed length and the width between the wheel wells, turned either way. The check turns it the way that uses less bed length.
• Bed length: Ford, Nissan, and Chevrolet give the length at the floor. Toyota gives “bed length” and Honda gives the length with the tailgate up, without saying where they measure. Toyota's dimensions pages list lengths without bed names, so we matched each length to a bed by size.
• Height: the tank top is compared with the height of the bed sides. A tank that rises above the sides can stop a flat bed cover from closing.
• Not checked: the Ralda's listing does not label which side is the height, so its footprint is unknown.
• Not listed: the Ram 1500 and Chevrolet Silverado 1500 pages we could read give no width between the wheel wells. Measure your bed and enter it above.
• Not included: straps, mounts, hoses, and the room you need to reach the lid and outlet. Payload is also not checked. Use the planner above with the payload from your door label.

Sizes were read on October 20, 2026 from each maker's spec sheet, press kit, brochure, or dimensions page. Each row shows the model year its source covers. Beds change between model years and trims, so measure your own bed before you buy. A fit here compares listed sizes only. It does not approve a mounting or a load.