1800 Litres Underground Water Tank
Specification
| Weight - kg | 88 |
|---|---|
| Length - mm | 2080 |
| Width - mm | 1260 |
| Height - mm | 1360 |
| Capacity - Litres | 1800 |
| Capacity - Gallons | 400 |
| Suitable for Drinking Water (Potable) | Yes |
| WRAS Approved | No |
| Construction Material | Polyethylene |
| Neck Diameter - mm | 600 |
Details
Our 1800 Litres Underground Water Tank complies with EU and UK regulations and is manufactured in the UK from high strength polyethylene. Moulded using a rotational moulding process, this tank is mainly used for storing harvested rainwater; however, it can also be used for storing water from other sources such as springs and wells.
Designed with strength in mind, it is shorter 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 ongoing care, these tanks have a long lifetime ahead of them with very little or no maintenance required.
Optional telescopic neck, lid and calmed inlet drainage pack
As standard, this tank is supplied as a plain tank with no accessories or fittings. The optional 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.
The calmed inlet drainage pack includes a rainwater filter and is designed to filter incoming rainwater and helps prevent it from becoming stained and odorous. 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.
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.