Valeting water tanks: sizes, baffles and cars per fill

Estimate water demand and choose a tank around usable supply, carrying capacity and maintenance access.

By the Mobile Detailer Equipment team · Updated 2026-10-25

Choose tank capacity from water demand and the van's available carrying capacity. The largest tank that fits may leave too little weight margin or room for the rest of the rig. Estimate a representative day, then check the complete loaded vehicle before committing to a permanent installation.

Estimate litres from trigger time

Use the washer's documented flow in litres per minute. Divide litres per hour by 60 if necessary. Multiply by the expected minutes with water flowing, then add other uses. Brushing, waiting and moving around the vehicle are not automatically trigger-on time.

For illustration, entering 7 litres per minute and 8 minutes gives 56 litres of spraying. Four identical example jobs give 224 litres before other uses. This is arithmetic, not an expected consumption figure for a particular service. Different vehicles, appointments and working methods change the inputs.

Use the rig matcher to compare a day with a refill against a day without one. A confirmed refill can reduce departure water, provided the route and access make it practical. Include time for filling in the booking plan rather than assuming it happens instantly.

Separate capacity from usable supply

Nominal capacity does not establish how much water the installation can deliver reliably. Outlet position, tank shape and washer inlet requirements affect the arrangement. Ask the supplier how the proposed tank will be filled, vented, drained and inspected. Check how remaining water will be observed during work.

Confirm the washer supports the planned feed before ordering plumbing. Keep isolation accessible and protect connections. Establish when to stop before supply becomes inadequate, and follow the machine instructions for priming and restarting. Include filters and other required components in the installation plan.

Include installed weight

For practical planning, water adds about one kilogram per litre. Include the tank, frame, fittings and enclosure as well. Add people, fuel, machines, chemicals, reels and shelves. The payload planner organises these entries; a loaded weighing checks the actual outcome.

Use the vehicle's plated gross and axle limits. GOV.UK explains vehicle weight terms. Read definitions carefully so people, fuel or equipment are neither omitted nor counted twice. Allow for routine additions and any recovered liquid you will carry after an appointment.

Ask installation questions

Discuss load distribution and tank position with a competent fitter. Ask what structural mounting points and restraint system suit the complete installation. Establish maintenance access before building shelves around it. The tank should remain inspectable, with a practical route for eventual removal.

Discuss baffles with the supplier as a feature of the intended installation. They do not replace suitable restraints or weight checks. Ask what use the tank is designed for and how it must be supported. Do not assume a stationary-storage container is suitable for vehicle transport.

Review real consumption

Record departure and finishing levels, refills and jobs completed. Include difficult appointments rather than relying on the easiest day. Revise the fill and refill routine from those records. If demand exceeds carrying capacity, change the schedule or service arrangement before increasing the tank. Reliable water access is more useful than a capacity the van cannot sensibly carry.