1800 Litres Direct Pressure Underground Rainwater Harvesting System
Specification
| Weight - kg | 88 |
|---|---|
| Length - mm | 2080 |
| Width - mm | 1260 |
| Height - mm | 1360 |
| Capacity - Litres | 1800 |
| Capacity - Gallons | 400 |
| Suitable for Drinking Water (Potable) | No |
| WRAS Approved | No |
| Construction Material | Polyethylene |
Details
This complete 1800 litre direct pressure rainwater harvesting system is ideal for collecting and storing rainwater to use in your home for tasks such as flushing the toilet, washing clothes or washing dishes. The 1800 litre system is suitable for smaller installations such as a 2 bedroom house.
The Direct Pressure system works by supplying water directly to the point of use, for example when a toilet is flushed the pump starts running and rainwater from the tank is pumped to refill the cistern. The pump automatically stops once the pressure in the pipework has been restored. Should the rainwater in your tank reach a low level, a small amount of mains water is sent to the rainwater tank, therefore leaving maximum capacity available for the next rainfall.
This system includes:
- 1800 litre polyethylene tank
- B Series stainless steel submersible pump with float switch
- Rodent guard
- Calmed inlet drainage pack with rainwater filter
- Pump turret
- Pump lifting chain
- Floating intake
- Automatic mains water top up controller
1800 Litre Tank
The 1800 litre tank is rotationally moulded from high strength polyethylene and complies with EU and UK regulations. Designed with strength in mind, it is shorter in height compared to other tanks on the market today. This means that a shallower hole is needed to accommodate the tank, and this can be by as much as 500mm less.
Features:
- 1800 Litre / 400 Gallons capacity
- Made in the UK
- Made from high strength polyethylene
- Ribbed and curved design provides added strength and efficiency
- Low profile means a shallower dig is required
- Large 600mm diameter access allows inspection and maintenance
- Easy to install with environmentally friendly pea gravel backfill
- Ideal for areas with a high water table
- 10 year warranty
The ribbed design provides added strength and efficiency, while also allowing for an environmentally friendly pea-gravel backfill, eliminating the need for a time consuming and high cost concrete base and backfill to be used. The curved element of the design also enables all water, even from the bottom of the tank to be pumped out.
These tanks are amongst the most dependable on the market and as such are supplied with an industry leading 10 year warranty. With the correct installation and general on-going care, these tanks have a long lifetime ahead of them with very little or no maintenance required.
Telescopic Neck and Lid
The telescopic neck and lid push fits into the neck of the tank and a rubber seal located towards the bottom ensures a tight fit. The telescopic part of the neck can be extended by up to 300mm and can be tilted in any direction by up to 5 degrees.
In-Tank Filter with calmed inlet
As standard, a PF filter is pre-installed into the neck of the tank. The filter removes leaves, grit and other debris from the rainwater passing through. The filter requires very little maintenance, usually about 3-4 times each year and is very quick and easy to clean with no consumables, just lift, rinse and replace.
The calmed inlet slows down the speed the water enters the tank and introduces the water into the lower part of the tank. As a result of this controlled entry, the water does not disturb any sediment at the base and replenishes the supply of oxygenated water throughout the tank, not solely at the top. This keeps the water inside the tank fresher for longer.
Submersible Pump
This system is supplied with a B Series stainless steel submersible pump which sits in the bottom of the tank and has sufficient power to service most garden based water requirements such as hoses and irrigation.
The pump combines with a float switch to help protect the pump from running dry and potentially causing damage.
Pump Lifting Chain
This allows you to quickly and easily pull the pump up towards the top of the tank for maintenance or inspection purposes.
Pump Turret
The pump turret is a flexible plastic connection between the pump and access port which allows smooth flow of the pumped water out towards its point of use.
Mains Water Top Up Controller
The top up controller kit detects when the tank water level is running low and initiates a mains top up procedure to ensure the tank never runs out of a water supply.
Floating Intake
A floating intake ensures that no water from either the surface or bottom of the tank is taken into the pump. This means that only clean water passes through the system and is pumped to the point of use.
Rodent Guard
The rodent guard protects the water inside the tank from rodents and large debris which could contaminate the water by entering via the overflow.
Important Delivery Information
Please note the price of this tank includes delivery to an address in England or Wales. Deliveries to Scotland, Northern Ireland and offshore islands may incur a surcharge. Please contact us for delivery charges to any of these locations.
The delivery will be unloaded from the vehicle by the delivery personnel; however, responsibility then passes on to the customer to move the tank in to position.
FAQs
What is an underground water tank?
An underground water tank is a buried polyethylene tank used to store rainwater or mains-top-up water below ground level. This model uses a shallow-dig design that saves surface space while providing large-volume storage for domestic and commercial sites.
How do underground water tanks work?
Rainwater flows from downpipes through a filter which removes leaves and other debris before entering the tank. Water is then drawn out by a submersible pump or suction line to supply garden taps, washdown points, toilets or other non-potable applications. The ribbed structure provides strength against pressure, which allows it to be stored underground.
Is this tank suitable for rainwater harvesting?
Yes. When paired with the correct filter, calmed inlet and pump/control unit, this tank becomes the main storage vessel in a full rainwater harvesting system for homes, schools and commercial buildings. The shallow-dig profile reduces excavation depth and installation cost.
What can an underground tank be used for?
Common applications include:
- Garden and landscape irrigation
- Vehicle, equipment and yard washdown
- Toilet flushing through a header tank or control unit
- Process water for workshops and light industrial sites
- Backup storage where mains supply is unreliable
Can this tank store drinking (potable) water?
The tank is manufactured from potable-grade polyethylene. For drinking-water use, you must specify the potable lid/neck kit and ensure filtration, disinfection and pipework comply with UK Water Regulations. Seek guidance from a qualified specialist before using stored water for consumption.
How is the tank installed?
This is a shallow-dig tank and typically requires no concrete base. Installation involves:
- Preparing a level excavation to the specified dimensions
- Lowering the tank into position and checking for level
- Backfilling evenly with pea gravel
- Adjusting the telescopic neck and lid to the finished ground height
Groundworkers must assess soil type, groundwater and loading before installation.
Do I need planning permission?
Most underground rainwater tanks fall under permitted development in the UK, so planning permission is usually not required. Always check with your local authority if the property is listed, in a conservation area, or if drainage layouts are being altered. Building Regulations still apply where the system connects to internal plumbing.
Can vehicles drive or park over this tank?
Yes — as long as the correct vehicle-rated lid and neck assembly is used and the tank is installed to the specified cover depth with the correct backfill. For landscaped or pedestrian areas, a standard lid is normally sufficient.
How do I pump water from the tank?
Most systems use a submersible pump inside the tank. This delivers water to hose points, washdown areas or a header tank. For commercial sites with higher demand, a matched pump and control package is usually recommended for stable flow and reliability.
How do you clean and maintain an underground water tank?
Routine maintenance includes:
- Cleaning gutters, leaf guards and pre-filters several times per year
- Checking pump strainers and calmed inlets (if fitted)
- Inspecting sediment levels through the 600 mm access neck
- Arranging a professional tank clean if contamination or odours are present
The curved base and calmed inlet help keep sediment undisturbed, improving long-term water quality.
How long do underground polyethylene tanks last?
This tank includes a 10-year manufacturer’s warranty. With correct installation, controlled loading and regular maintenance of filters and pumps, the expected service life is typically several decades. Avoiding vehicle loads beyond the design rating will maximise lifespan.