How to Choose the Best Plastic Water Storage Tank

30th September 2025 in water
Author: Jack Dunn

Selecting the right plastic water storage tank involves more than just picking the largest size you can afford. The right choice ensures clean water, efficiency, longevity and regulatory compliance. Use this guide to make an informed decision.

1. Decide on Use & Water Type

Ask yourself: is this tank for potable (drinking) water or non-potable (irrigation, washing, rainwater capture)? Tanks meant for drinking water must use food-safe materials and often need certification (e.g. WRAS approval in the UK) to confirm they don’t leach harmful chemicals.

2. Determine Required Capacity

Estimate daily or weekly water usage plus a buffer for supply interruptions. Also consider turnover: if water sits too long, quality may degrade. For homes, building standards suggest around 100 litres per bedroom for cold water storage tanks.

3. Material & Construction Quality

Most plastic water tanks are made from polyethylene (PE) — often HDPE or MDPE — due to their strength, chemical resistance and ease of moulding. Ensure the material is UV-stabilised to resist sun damage. Look for rotationally moulded or blow-moulded construction, which gives a uniform wall thickness.

4. Shape, Orientation & Footprint

Tanks come in vertical (upright), horizontal (cylindrical), flat, D-shape or rectangular styles. Choose a shape that fits your space and load constraints. Some are designed to spread the load (flat types), others to conserve ground space (upright).

5. Access, Fittings & Design Features

Look for these practical features:

•   A tight, opaque lid to keep out light, dust, insects and vermin
•   Vent or breather pipe with insect screen
•   Overflow ports sized and arranged to avoid backflow
•   Inspection hatches or manholes for cleaning access
•   Baffles or internal reinforcement in large tanks to prevent bulging or structural strain if transported
•   Pre-drilled outlets or the option for plastic fusion sockets to add custom connections later

6. Installation & Base Requirements

The tank must sit on a clean, level, stable base (concrete slab, reinforced base). Uneven or soft ground can lead to cracks or distortion. Also ensure access for plumbing, servicing and cleaning.

7. Regulation, Compliance & Safety

If using for drinking water, ensure the tank is constructed from approved materials, has the correct markings (e.g. Water Regs UK, WRAS) and meets local water regulations. Tanks should be protected from sunlight and heat, and inspected regularly for any damage or sediment accumulation.

8. Maintenance & Lifespan

A good quality plastic tank, when well maintained, can last a decade or more. Inspect seals, lids, screens and surfaces periodically. Clean, flush and disinfect (as needed) to prevent algae, sediment or bacterial growth.

The best plastic water storage tank is one that matches your intended use, capacity needs and installation environment, while meeting safety and compliance standards. By considering material quality, design features and ongoing maintenance, you can ensure reliable performance and long service life. At Tanks R Us, we offer a wide range of durable, UK-compliant water tanks to suit every application. If you’re unsure which option is right for you, our team is ready to guide you toward the perfect solution.

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