GARDENA Rain Water Tank Pump 4000/1

The GARDENA Rain Water Tank Pump 4000/1 is a submersible pump that drops into a rain barrel, a water tank or an IBC container and moves the collected rainwater where you want it: onto the garden, into a watering can, or out of the tank altogether. GARDENA describes it as a pump that lets you use collected rainwater from a barrel or tank to water your garden, and says it is versatile enough for various garden watering and drainage tasks¹.

For a household preparing for emergencies, that second use is the one worth knowing about. A pump that can empty a tank down to a water depth of just 5 mm, using its continuous-on function, is a pump that can clear a barrel before a freeze, drain stored water after a flood, or move a large volume of water quickly when the mains supply is interrupted². It is not a drinking water treatment device and it does not make rainwater safe to drink; it moves water.

The headline figures are 400 W of power, a maximum delivery capacity of 4000 l/h and a maximum pressure of 1.3 bar³. It fits through 150 mm openings, such as those on IBC containers, and stands 64.3 cm tall¹. This page sets out what it does, what the specifications mean in practice, how to keep the filter clear and how to use and store it safely.

What the pump does for a household

Think of the pump as the moving part of a rainwater system. A water butt collects water; the pump takes it from the butt to the plants, the hose or the drain. GARDENA lists the jobs it will do: filling watering cans, running sprayers and showers, feeding small sprinklers, the Micro-Drip-System and the Aqua oscillating sprinkler, as well as draining³. In an ordinary year that is garden watering. In an emergency it is a way of moving stored water without carrying buckets.

The pump comes with a regulating valve, so you can adjust the flow rate or stop the water flow completely, an integrated fine filter and an aluminium telescopic pipe². The telescopic pipe adjusts between 615 and 815 mm and drains the collected water over the rim of the barrel without blockages². That pipe is what lets the pump sit in a deep barrel and still deliver water over the side.

Where does this fit a household plan? If you keep water butts as part of your stored water, the pump is what turns them from a static reserve into something you can actually use: filling containers, watering a garden that may be your food supply in a long disruption, or emptying a barrel that has become a mosquito-breeding liability in a hot spell. For the wider picture of what harvested rainwater can and cannot be used for, see what harvested rainwater can be used for.

Specifications: 400 W, up to 4000 l/h, 1.3 bar

The maker's figures are the ones to work from. GARDENA gives the power rating as 400 W, the maximum delivery capacity as 4000 l/h and the maximum pressure as 1.3 bar³. The maximum delivery head is 13 m³. Read those together rather than separately: 4000 l/h is the flow at the pump with no height to push against, and the 13 m head is the height it can lift to with no flow. Real use sits somewhere between the two, and a long hose run or a tall lift reduces the flow you get.

A pump that is rated for immersion and built with a stainless shaft is one you can leave set up in a barrel through the season, provided you follow the maker's instructions on frost and storage.

Emptying rain barrels, tanks and IBC containers

The pump's most useful property in an emergency is that it empties a tank almost completely. GARDENA states that the continuous-on function allows the tank to be emptied down to a water depth of just 5 mm². A barrel you can drain to 5 mm is a barrel you can dry out, clean and put away before winter, or empty of standing water after a flood when stagnant water becomes a health problem.

It fits through 150 mm openings, for example in IBC containers¹. That matters if you store water in an IBC: the opening is narrow, and a pump that will not pass through it is no use. Check the opening on your own container against the 150 mm figure before you rely on it.

The pump also has an adjustable float switch that switches it off when water falls below a set level, to prevent dry running damage¹. That is a safety feature for the pump, not a substitute for watching it: set the float so the pump stops before it runs dry, and check the setting each time you drop it into a new container.

A practical order for emptying a barrel or tank:

1. Check the float switch is set and free to move, so the pump cuts out before it runs dry¹.
2. Lower the pump into the tank, keeping the cable clear of the rim and any sharp edges.
3. Fit the telescopic pipe and adjust it between 615 and 815 mm so water drains over the rim without kinking³.
4. Open the regulating valve to start the flow, and close it to stop the water completely when you have finished³.
5. Let the continuous-on function take the level down to about 5 mm, then switch off and lift the pump out².

For the wider question of how a rainwater system behaves when the power itself fails, see will a rainwater system keep working in a power cut. The short answer for this pump is that it is mains powered: no electricity, no pumping.

Keeping the fine mesh filter clear of blockages

GARDENA fits an integrated fine filter that is easy to remove and clean, and says the pump is protected against blockages by it¹. That filter is the pump's first line of defence against grit, leaves and sediment, and it is the part most likely to need your attention.

The case for keeping debris out of the tank in the first place is strong. Rainwater filters prevent leaves, moss and other debris from entering the rainwater storage tank and reduce the build-up of sediment, according to Enduramaxx⁴. Their filter kits are described as preventing moss and leaves from going into your rainwater harvesting tank while softening the water as it passes through the filter⁵. A downpipe or in-tank filter upstream of the pump means the pump's own fine filter has less to catch.

Filter makers also warn about the opposite problem: a filter that blocks quickly is usually dealing with very dirty feed water, such as water carrying a lot of mud, silt, algae or sewage, and the advice is to pre-filter dirty water and keep a small amount of clean water inside the product⁶. The same logic applies to the pump's fine filter: the dirtier the water going in, the more often you will be cleaning it.

For the full routine across a year, see keeping a rainwater system clean and working, and for the filter types themselves, rainwater filters.

Using it safely: power, water and the limits of the pump

This is a mains-powered electrical appliance designed to sit in water, so the safety rules are the maker's and they matter. GARDENA rates the pump IP X8, which is a rating for immersion, and supplies it with a 10 m H05RN-F cable¹. The cable length is a safety feature as much as a convenience: it lets you reach an outdoor socket without joining cables or trailing an extension lead across wet ground.

The maker's own limits are the ones to keep to. The maximum liquid temperature is 35 °C, so do not use the pump on hotter water¹. The float switch is there to prevent dry running damage, so set it and leave it to work¹. The regulating valve lets you stop the flow completely, which is the right way to pause the pump rather than pulling the plug on a live unit³.

On storage, the maker's instructions for this model should be followed, and the pump should be cleaned and drained before it is put away. The integrated fine filter is easy to remove and clean, which makes the end-of-season clean straightforward¹. Keep the cable coiled loosely rather than tightly kinked, and store the pump where it will not freeze.

Support, article number and warranty

GARDENA lists the Rain Water Tank Pump 4000/1 under article number 1762-28¹.

The barcode is similarly unsettled. GARDENA gives the GTIN-13/EAN as 4066407025806 on its UK product page, while a second GARDENA page lists 4078500047821 for the same model¹. The two do not match, so treat the barcode as a guide and confirm the model name and article number with the seller.

For support, warranty terms and spare parts, go to the maker: GARDENA's own product page for this pump carries the current documentation, and the GARDENA brand page gathers what the site covers on the maker's range. Keep your proof of purchase with the pump's paperwork, and note the article number on it.

Where the pump sits in a wider plan: it is one part of a rainwater system, alongside the tank, the filter and the pipework. If you are starting from scratch, rainwater harvesting at home explains how the parts fit together, pumps for rainwater tanks sets submersible and surface types side by side, and the garden rainwater harvesting kit checklist lists what to gather before you need it. For the household view of stored water in an emergency, see water in an emergency.