Rainwater Harvesting - helping to conserve precious water resources

Water, or more precisely its scarcity, is an issue that needs to be urgently addressed by the government, regulators and water utility companies alike. Climate change, over extraction of water and population growth are largely to blame for the current and future areas of water stress in the UK, most notably in London and the South East. Water efficient technologies like rainwater harvesting and greywater recycling enable us to reduce the water consumption by utilising – rainwater from the roof or re-using water from roofs and draining from hard standing areas.

Water companies often implement short term reactive measures to combat water stress e.g. hose pipe bans. Unfortunately the general public forgets about the water issues the minute its starts raining again. Here at Aquality we pride ourselves in offering proactive solutions  that conserve water and ease pressure on resources in the long term.

Why not make use of them? 

How a rainwater harvesting system works

Rainwater is collected from the roof and collected via the gutter, outlet or siphonic drainage system. Before the water enters the storage tank it is filtered to remove large particles such as leaves, moss and twigs.

The filtered water is  then fed into the storage tank via a calmed inlet, this ensures that the water discharging into the tank stays calm allowing small particles to settle to the bottom or float to the surface.

The water is then pumped to the serviced appliances via a floating filter extraction point that remains below the surface level of the water but above the bottom of the tank, this ensures the pump water remains free of sediment.

Rainwater harvesting

Rainwater harvesting – Water Quality

A professionally designed and installed rainwater harvesting system will deliver water quality that will be more than sufficient for non potable applications such as WC flushing, laundry etc. More information on water quality  values are available in BS8515:2014:+A1 Code of Practice for Rainwater Harvesting.

Rainwater harvesting system components

Pre-Filtration – Filtering out larger debris such as leaves
Rainwater storage tank – collects and stores the incoming rainwater
Supply pump (optional) – supplies water from storage tank to control unit unless tank is close enough to tank to prime directly
Aqua-Control – Control unit with integrated booster pump set and mains water back-up according to BS8515
Expansion vessel – Reducing run time of pumps and protecting equipment against small leaks
Soak away (optional) – Infiltration system with pre-sedimentation pit
      1. Pre-Filtration
Filtering out larger debris such as leaves
      2. Rainwater storage tank
Collects and stores the incoming rainwater
      3. Supply pump (optional)
Supplies water from storage tank to control unit unless tank is close enough to tank to prime directly
      4. Aqua-Control
Control unit with integrated booster pump set and mains water back-up according to BS8515
      5. Expansion vessel
Reducing run time of pumps and protecting equipment against small leaks
      6. Soak away (optional)
Infiltration system with pre-sedimentation pit

Rainwater harvesting benefits

  • Reduction in mains water usage – saving money
  • Complies with BREEAM, LEED, & WRAS requirements
  • Energy efficient
  • Inert – no use of chemicals
  • Flood reduction
  • Can be combined with our greywater recycling systems
  • Compact and easy to install
  • Can accommodate any building due to flexible above or below-ground storage systems
  • Enhanced Capital Allowance applicable via Water Technology List

Different systems for different requirements 

Aquality offers a wide range of re-use systems for all types of buildings such as:

  • Educational buildings e.g. schools, universities, colleges, student accommodations
  • Retail buildings e.g. supermarkets, warehouses, distribution centres’
  • Public buildings e.g. police, fire stations, prisons, council offices
  • Other commercial buildings

Different types of buildings may require different types of systems, such as:

  • Above/below ground systems
  • Gravity/direct systems
  • Rainwater/Greywater
  • Attenuation/Combined systems

Rainwater Harvesting Pre-Filtration

Efficient manual or self-cleaning rainwater harvesting filters with low invert levels

Aquality offers a range of rainwater filters to suit roof areas from 150m² to 60,000m². These filters can be installed into rainwater harvesting underground tanks , or within the building in free standing storage tanks.

Unless maintenance can be guaranteed to be carried out regularly then we recommend that filters are equipped with a self-cleaning mechanism. These can be semi or fully automatic, the majority of our filters are pre-fitted with semi/fully automatic cleaning facilities.


Our commercial filters have been developed for large rainwater harvesting systems and designed to cope with flow rates up to 1800 l/s. The filters use a bespoke stainless-steel grid with a 0.7mm filter mesh.

The filter grids have been designed so that they make perfect use of the water molecule characteristics this allows water to pass into the storage tank at 99% rate of efficiency. The filter reduces potential maintenance by separating organic dirt particles such as leaves, moss & twigs and preventing them entering the tank.

Inevitably over time some particles will get stuck in the filter grid, and this debris will need removing periodically. As most filters are fitted in underground tanks or in confined areas , we recommend that a semi-automatic or fully automatic cleaning system is used. The majority of Aquality filters are semi or fully automatic and can be used in conjunction with our control units.

AWD Filter - Automatic Water Diversion

The Automatic Water Diversion (AWD) filter bypasses water from the rainwater harvesting tank when it is at full capacity by using a patented airlock. It is ideal for use where a conventional overflow is not the preferred solution.

  • Filter with high collection efficiency
  • Stainless steel grid
  • Automatic water diversion
  • Ideal for combination with greywater recycling systems complying to BS8525

Rainwater harvesting storage tanks

Water storage tanks for every application
500 – 400,000+ litres capacity in a single tank

An essential component in any rainwater re-use solution is the tank, although it is easy to think that all the tank does is hold water, it is important to understand that the tank through the incorporation of calmed inlets plays a critical role in providing the right water quality values.

Aquality, who are members of the UKRMA, offer complete rainwater harvesting solutions and offer a range of BS8515 compliant tanks from GRP, PE, PP and concrete, free standing or below ground. The selection of the tank will be site specific and will consider amongst other things structural loading, ease of transport and installation. Tanks may come complete with pre-fitted filters to reduce drainage inverts.

For above ground or free-standing applications, we recommend our range of sectional or single piece GRP or PE Tanks.

GRP tanks can also be used below ground and backfilled with pea gravel or concrete, however the specification of the tank should be discussed as early in the design stage as possible to ensure it is cost effective and delivers the design objectives.

Rainwater Harvesting Aqua-Control units

Rainwater Harvesting - Compact booster pump set with integrated mains water back-up and controls

Aqua Control units have been developed to ensure a compact, easy to install product that accommodates all the necessary features of a modern rainwater / greywater control unit. They are purpose designed for each application to ensure integrated solution is delivered.


The Aqua Control unit has an integrated break tank, booster set and electronic control.

The control unit monitors the level in the rainwater and mains back up break tank, and the self-priming booster pump set supplies water directly to the appliances.  In the event of a shortage of rain or greywater, or where a manual setting has been employed the AC unit feeds mains water, via an AA-type air gap, into the tank in accordance with BS8515 or 8525.

If the solenoid valve in the mains water back-up system has not regularly opened,  then the AC unit is programmed to flush the mains water pipe to avoid stagnation, this pre-set standard can be altered to meet project specific needs.

In addition, the units have a manual over-ride for maintenance and an automatic over-ride in case of supply failure from the tank.

Aqua Control (AC) units are designed primarily for commercial rainwater harvesting  schemes, and have been built with operational safety, reliability and energy efficiency in mind, and include in-depth monitoring capability for modern facility management.

The AC units have been successfully employed in schools, offices, supermarkets, airports and sports stadia.

Our Aqua Control 5000 unit offers superior functionality  and can be customised for site specific requirements.