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 a diagram of a rainwater harvesting system in a supermarket using a central tank for the collection and reuse of rainwater

Commercial & Non Household Solutions

Many commercial and non-household buildings are ideal for rainwater harvesting including…

  • Schools
  • Offices
  • Hospitals
  • Supermarkets
  • Distribution centres
  • Manufacturing sites
  • Many other commercial building types


 a community rainwater harvesting diagram using a single tank to supply rainwater to each home.

Communal & Residential Solutions

Rainwater harvesting can be utilised on many residential developments including…

  • Housing developments
  • Student accommodation
  • Hotels
  • Holiday villages
  • Apartments


 a diagram of a rainwater harvesting which has been retrofitted to an existing building using above ground installation methods

Retrofit Solutions

Rainwater harvesting can be retrofitted to many existing building types including…

  • Supermarkets
  • Schools
  • Manufacturing sites



Information Guide for Rainwater Harvesting

Rainwater, not to be confused with greywater, is the collection of rainfall from the roof area of the building for reuse as a non-potable water supply.

Yes! There are many benefits to combining the technologies of Rainwater Harvesting and Greywater Recycling.

Rainwater and Greywater can be mixed through a Combined System. These are highly specialist systems and should be specified in collaboration with a Stormsaver specialist.

On Combined Systems, rainwater and greywater are treated separately in their respective filtration devices and supplied into a central header tank complete with a mains water top up.

Do I have a header tank?  Not all Rainwater Harvesting Systems are designed with a header tank. The space within some buildings is so limited that a header tank simply cannot be located within the building. Where there is no space for a header tank, a pressurised or Combi-style system will be used to provide internal capacity. Take a look at our commercial and non-household solutions to learn more about the different system arrangements.

If you have a system already installed, one of our specialist engineers can complete a system assessment to determine your system type. Learn more here.

Can I have more than one header tank? Yes, with a Stormsaver system, a range of individual tanks can be installed around the building – up to seven in total with a standard d unit. Should more be required Stormsaver can supply a bespoke package for additional tanks.

Communal systems typically utilise multiple header tanks to supply rainwater throughout the whole housing development.

Can the header tank be located at a low level? A header tank can be fitted anywhere in the building. If it is on the ground floor or basement level a booster pump can be used to distribute the water to points of use – rather than the use of gravity direct from the tank.

In fact, many specifiers prefer to design systems with a header tank at a low level to prevent the risk of legionella development. The risk of legionella development is greater in higher locations due to higher temperatures.

Where locating a header tank high up is unavoidable, we can provide additional protections such as continued circulation of UV disinfection. Just ask our team.

Can the header tank be located on the roof?  A header tank can be fitted on the roof of a building – if this is the case we would recommend increasing the insulation from the standard 25mm up to 50mm to prevent freezing or warming. Any pipeworks to the tank also require insulation and or trace heating.

Do I need to insulate internal pipework? Yes, internal pipework within the building should be insulated, any pipework installed externally if above ground should be isolated or trace heated to prevent freezing or warming.


What pipework should be used inside the building? It is recommended that when piping up the rainwater system that a different pipework material is used on the rainwater pipework to the mainswater pipework, this is to avoid accidental cross-connection of the two supplies at a later date. Stormsaver can provide WRAS approved pipework identification tape to apply to pipework to avoid any confusion of the contents and it is a requirement that this is used.


What type of pipework should be used underground? All rainwater harvesting supply pipework should be in WRAS approved black and green or clearly identified with black and green tape. Under no circumstances should pipework from the tank be run in blue.

Water savings are highly dependent on several factors including roof area, local rainfall, and demand within the building.

Reusing rainwater can save as much as 75% on mains water consumption. This figure is determined through live monitoring of Stormsaver’s 2,000 rainwater harvesting systems.

Stormsaver specialists can provide potential water-saving figures according to your bespoke project. Just ask our team.

As per the British Standard recommendations, systems should receive regular inspections.

Based on our experience, Stormsaver recommends bi-annual servicing for functional testing of the control panel and cleaning of filtration devices. Tank cleans are also required every 2 years depending on the site location. Sites located near heavily forested areas may require more frequent cleaning.

Stormsaver provides maintenance services for all types of rainwater harvesting systems. Find out more here.


Yes! Rainwater Harvesting is ideal for symphonic drainage as all roof water can be directed to one outlet which is connected to a rainwater harvesting storage tank, therefore reducing pipework installation and groundwork costs.

It is important to understand the large flow rates and velocity of the water in the symphonic system in the drainage design process. Our team of specialists recommends breaking the siphon before our pre-tank filter via a vented siphon break.

Our Added Value Options

Looking for additional filtration, UV disinfection, or installation services? Our added value options give you access to best-practice approaches. Learn more here. 

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Constructionline Gold Member CHAS Accredited UK Rainwater Harvesting Association Member Safecontractor Approved Waterwise Affiliate UK Business Awards Winner 2022