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Campervan Water Calculator
Size Your Tanks

Estimate your campervan's daily water consumption.
Calculate your off-grid autonomy and size your fresh and grey water tanks accurately. 100% free tool.

๐Ÿ—บ๏ธ Trip Profile

People
Dogs/Cats
Days

๐Ÿšฟ Equipment & Comfort

L / pers.
L / pers.
L / total
L / total
L / pet

โž• Specific water expenses

Add specific regular consumption (e.g., washing bikes, rinsing surfboards...).

Water consumption and storage

Fresh Water Tank Required
0 L
To last X days off-grid.
Grey Water Tank
0 L
Collects water from the sink and shower (drinking water and toilet water do not go here).

๐Ÿ“Š Daily Consumption

0
L / day

Water in a Campervan: Why Calculate Everything?

Managing water in a campervan is a daily reality for all vanlifers. While turning on a tap at home is taken for granted, off-grid living means every litre counts. Water represents a significant dead weight (100 litres = 100 kg, directly reducing your MTPLM and available payload) and a key logistical factor (finding fresh water fill points and grey water waste disposal stations across the UK).

Using our water requirements calculator before purchasing tanks ensures you size your build accurately. A tank that is too small forces daily searches for fresh water fill points, interrupting off-grid trips. A tank that is unnecessarily large adds excess vehicle weight, reducing fuel efficiency and eating into your legal 3.5-tonne weight allowance.

Understanding Your True Consumption: Shower vs. No Shower

The difference in daily water consumption between conversions comes down almost entirely to one feature: the indoor shower.

  • In "Eco" Mode (No Shower): Using a washbasin or flannel for washing, two people can manage on 10 to 15 litres per day (drinking, tea/coffee, cooking, and basic washing up). A 60L fresh water tank provides around 4 to 5 days of complete off-grid autonomy.
  • In "Comfort" Mode (With Shower): Even when water-conscious (turning off the tap while lathering, using low-flow aerators), a quick shower uses 5 to 12 litres per person. The total requirement for two people rises to 30 to 40 litres per day. In this configuration, a 100L fresh water tank is the minimum size required for 3 days off-grid.

Did you know? Your grey water tank (wastewater from the sink and shower) always requires a smaller capacity than your fresh water tank. Water used for drinking, cooking pasta, or pet bowls does not enter the grey waste system. As a result, a grey water tank sized to 70%โ€“80% of your fresh water capacity is standard practice.

๐Ÿ’ง Design the Perfect Water System

Diaphragm pumps, accumulator tanks, hot water... Discover how to install the tanks you have just sized in our complete plumbing guide.

Read the Plumbing & Heating Guide โ†’

FAQ: Campervan Water Systems

How many litres of water do you use per day in a campervan?

On average, a single person in a campervan uses 15 to 20 litres of water per day if taking a quick shower, cooking, and washing up. Without an indoor shower, daily consumption drops to just 5 to 6 litres per person (drinking, cooking, and basic washing).

What size fresh water tank should a couple choose?

For two people seeking 3 days of complete off-grid autonomy with a daily shower, an 80 to 100-litre fresh water tank is the recommended standard. If you don't have an indoor shower, a 40 to 50-litre tank is more than enough for a long weekend off-grid.

Does water take up a lot of payload weight?

Yes, water is one of the heaviest elements of your conversion. Fresh water has a density of 1 kg per litre, meaning a full 120-litre tank adds 120 kg directly to your vehicle's overall weight, reducing your remaining legal payload under your 3.5-tonne Gross Vehicle Weight (GVW / MTPLM) limit. Mount water tanks as low as possible and over an axle to maintain safe vehicle handling.

Does the grey water tank need to be the same size as the fresh water tank?

No, a grey water tank can be smaller. A significant portion of fresh water is consumed for drinking, boiling food, or pet bowls, meaning it never enters the grey waste system. Sizing your grey water tank to 70%โ€“80% of your fresh water tank capacity is standard practice.

How can I save water on a road trip?

To maximize off-grid autonomy, fit low-flow tap aerators, install a trigger shower head (to pause water flow instantly while lathering), reuse vegetable washing water, and wipe greasy cookware with paper towels prior to washing up to minimize rinsing volume.

Do I need anti-surge baffles in my water tank?

Yes, especially for tanks larger than 50 litres. Water sloshing inside an unbaffled tank creates significant kinetic force during cornering and braking, which unbalances the vehicle. Internal baffles (or anti-surge baffling balls) restrict liquid movement and stabilize handling.

Where should I install my water tank in the van?

For fresh water, the ideal location is inside the living area (under the bed frame or garage bench) to prevent winter freezing. Position the tank as low as possible and over or just ahead of the rear axle to maintain correct weight distribution and a low centre of gravity.

Do I need to clean my fresh water tank, and how often?

Yes. Disinfect your fresh water system (tank, pipework, and pump) at least twice a yearโ€”ideally before the start of the season and prior to winter storage. Use food-grade tank steriliser or citric acid solutions to prevent biofilm and bacterial growth.

Which water pump should I choose: submersible or diaphragm?

Submersible pumps sit inside the water tank; they are affordable, quiet, and operated via microswitched taps, making them ideal for compact builds. Diaphragm pumps (like Shurflo) are pressure-demand units mounted externally; they maintain pressurized lines (1.5โ€“2.5 bar), supplying consistent flow for water heaters and showers across multiple outlets simultaneously.

How do you manage safe drinking water in a van?

Many vanlifers separate main tank water (used for showers and washing up) from drinking water. Options include using fillable drinking water jerrycans with dedicated taps, gravity filtration jugs, or installing an inline water filter (such as an active carbon and ceramic cartridge filter) directly onto your galley cold tap line.

The Plumbing Workshop