An IBC container as a water source for a pressure washer: how to choose the right pump, filtration system and flow rate

An IBC container as a water source for a pressure washer enables cleaning work to be carried out at sites where there is no fixed water connection. However, a fully functional system requires more than just a tank and a hose: the pressure washer’s water demand, the feed pump’s output, the suction head, filtration and the size of the connectors must all be coordinated. Careful sizing prevents pressure fluctuations, pump cavitation and damage to the pressure washer.

The mobile washing unit is used on farms to wash machinery and buildings. In property maintenance, it can be used to wash courtyards, refuse shelters and tools. To transport the tank safely, a rack suitable for the intended use is required; you can read more about the dimensions of such racks on the Lootu Oy website from the ‘Water tank for a tractor’ page.

An IBC container as a water source for a pressure washer: start by assessing your water requirements

The stated water consumption of a pressure washer indicates how many litres the machine uses per hour. A pressure washer designed for professional use may, for example, consume between 600 and 1,200 litres per hour. If necessary, convert the value to a per-minute rate by dividing the hourly consumption by 60. For example, 900 l/h corresponds to a flow rate of 15 l/min.

The feed pump must supply at least the volume of water required by the pressure washer. In practice, it is advisable to allow for a margin of around 20–30 per cent in the flow rate, as hoses, filters, connectors and differences in height cause flow losses. If the pressure washer requires 15 l/min, the pump’s target output under operating conditions is around 18–20 l/min.

The capacity of the tank determines the continuous operating time. A 1,000-litre tank is theoretically sufficient for approximately 66 minutes at a flow rate of 15 l/min. The actual operating time is shorter, as the tank cannot usually be emptied completely and the work involves breaks.

Feed pump capacity, pressure and design

The function of the feed pump is to deliver water from the tank to the pressure washer’s inlet connection at a steady flow rate. The pump does not need to generate washing pressure, as the pressure washer’s own high-pressure pump does the actual work. A feed pressure of a few bar is often sufficient, but the permissible pressure range must be checked in the pressure washer’s user manual. Different models have different requirements for the water supply.

An electric diaphragm or centrifugal pump is suitable for many portable systems. A diaphragm pump can cope with fluctuations on the suction side and generates pressure, but its pulsating flow may require a pressure accumulator. A centrifugal pump delivers a steady flow when it can draw water freely from the tank. An internal combustion engine pump is suitable for sites where electricity is not available.

The pump’s rated flow rate alone does not determine its suitability. The manufacturer often specifies the flow rate under conditions where the back pressure and head are low. Check the pump’s performance curve to see the output at the pressure and head at which the unit is operating. The technical specifications and operating instructions for the pressure washer can be found, for example, From the Kärcher website.

The feed pump must supply a steady flow of water to the pressure washer even when the filter becomes clogged and the water level in the tank drops.

Suction height and hoses affect operational reliability

The pump should be positioned as close as possible to the bottom valve of the IBC container, and preferably below it. In this way, the water flows to the pump by gravity, and the pump does not need to draw water up through the suction hose. This makes it easier to start the pump and reduces the risk of cavitation.

Every bend, restriction and quick-connect fitting on the suction side increases flow resistance. Use a rigid, vacuum-resistant suction hose that does not collapse whilst the pump is running. The internal diameter of the hose should be at least the same size as the pump’s suction connection. At the same time, check the clear diameter of the valves and fittings. Practical measurements are covered in more detail in the guide Valves, couplings and hose connectors for IBC tanks.

An air leak on the suction side may interfere with the water supply, even if the connection is not leaking water outwards. Check the seals, screw connections and hose clamps before use. Fill the pump with water in accordance with the manufacturer’s instructions, unless it is a self-priming model.

An IBC container used as a water source for a pressure washer requires filtration

Sand, rust, plastic fragments or organic matter in the IBC container may block the nozzle and cause wear to the pump’s components. Fit a washable pre-filter between the tank and the feed pump, provided the pump manufacturer permits this. A fine final filter can be fitted after the feed pump and before the pressure washer. This ensures that the fine filter does not restrict the pump’s suction side.

The filter mesh size must protect the equipment without restricting the flow. The pressure washer manufacturer’s specifications determine the final filtration level. A transparent filter housing makes it easier to spot dirt, and pressure gauges on both sides of the filter reveal the pressure difference caused by blockages.

An IBC container used as a water source for a pressure washer must also have a clean usage history. You must not use a container that has been used to transport unknown chemicals for washing water. Rinse the tank, valve and hoses before use and whenever the system has been out of use for a long time.

Trial operation reveals design errors

Assemble the system so that the valves, filter and pump can be accessed without removing the tank. Secure the hoses so that they do not rub against the frame, tyres or lifting equipment. Protect the electrical connections from water and select cables of a suitable size based on the pump’s power consumption.

Carry out the first test run with a full tank and repeat the test when the water level is low. Use the pressure washer with the nozzle that requires the highest flow rate. Monitor the supply pressure, the sound of the pump, the condition of the hoses and the cleanliness of the filter. Intermittent flow, fluctuating pressure or an unusual noise often indicate an air leak, a blockage or a pump that is too small.

Record the configuration currently in use: pump model, hose sizes, filter mesh size, washer consumption and measured supply pressure. This information will facilitate maintenance and the procurement of spare parts. Once the IBC container, used as the water source for the high-pressure washer, has been correctly sized and tested as a complete system, the washing unit can be used at various locations on a farm or in property maintenance without the need for a permanent water connection.