Rainwater Harvesting Equipment Companies
Tanks, filters, pumps, and controls for building- and district-scale rainwater harvesting systems.
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Specialists in rainwater harvesting equipment
Providers whose services or self-declared specialties match this category.
Rainwater Management Solutions
United States
Rainwater Management Solutions is a United States supplier and system integrator with over 70 years of experience in rainwater and stormwater management. It designs and installs turnkey rainwater harvesting and greywater reuse systems for residential, commercial, industrial and agricultural projects, including filtration, UV disinfection and proprietary tank sizing.
Buyer's guide
The buyer's guide to rainwater harvesting equipment
Rainwater Harvesting Equipment: Filters, Tanks, Pumps, and Controls for Residential and Commercial Systems
Rainwater harvesting equipment encompasses the full component chain from roof collection to point of use: guttering and downpipes, first-flush diverters, pre-tank filters, storage tanks, calmed inlets, submersible pumps with floating suction, controls and level sensors, mains top-up devices, and distribution pipework. Pre-tank (above-ground) filtration: self-cleaning vortex filters (280 or 380 micron stainless steel mesh, hydraulic capacity 1.2 to 4.2 L/s) or downpipe filters remove coarse debris before tank entry while using roof flow to self-clean, returning retained solids to drain. Calmed inlet: submerged floating inlet with 350 to 500 micron filter inside the tank separates incoming water from settled sediment; ensures settled particulate is not disturbed during filling. Floating suction: pump draws from mid-tank depth (not bottom sediment layer), maintaining water quality at the outlet. UK compliant systems require WRAS approval mark on all components in contact with water supply.
Storage tanks for rainwater harvesting: above-ground (polyethylene, 100 to 10,000 L; UV-stabilised black or dark green to inhibit algae growth; WRAS-approved materials); below-ground (polyethylene, 3,750 to 10,000 L; concrete precast; GRP/fibreglass for large commercial volumes 20,000 to 500,000 L). Below-ground polyethylene tanks require traffic-loading specification (SLW 30 or SLW 60 per EN 1250) for installation under driveways or parking areas. GRP/fibreglass tanks (bespoke fabrication, BS 4994 design): suitable for large commercial and industrial volumes; multiple compartments; integral pump chambers. Concrete precast tanks (BS 5911): high durability, negative external groundwater pressure resistance, suitable for high-groundwater-table sites where polyethylene tanks require backfill restraint or anti-flotation anchoring. Tank inspection access: minimum 600 mm diameter manhole cover per BS EN 476.
Control systems and pumps for RWH: submersible centrifugal pumps (typical pressure 2.0 to 4.0 bar at 30 to 100 L/min for residential); pressure vessels (membrane expansion vessels, 8 to 24 L) maintain system pressure between pump cycles, reducing start frequency to extend pump life. Control units: monitor tank level via ultrasonic or float sensor; switch to mains top-up via solenoid valve when tank falls below low-level setpoint; provide mains supply via Type AA airgap (required by WRAS and Water Supply (Water Fittings) Regulations 1999) ensuring no cross-connection between rainwater and potable supply. Telemetry and remote monitoring (smart RWH controllers with app-based alerts): log yield, demand, and top-up volumes; detect pump fault conditions. Commercial systems: booster sets (2 to 4 pump duty-standby manifolds, frequency-controlled) with central control panel, remote monitoring via BMS or GSM, and automatic chemical dosing for Legionella control in large storage volumes.
Frequently asked questions
What equipment is needed for a complete rainwater harvesting system?
A complete residential RWH system comprises: (1) Pre-tank filter: self-cleaning vortex filter or downpipe filter on each collecting downpipe - removes debris, leaves, and coarse particles; (2) Storage tank: 2,500 to 5,000 L below-ground polyethylene tank or above-ground tank for smaller applications; (3) Calmed inlet: submerged floating inlet distributor with fine filter prevents disturbance of settled sediment; (4) Submersible pump: centrifugal submersible with floating suction filter (draws from mid-depth, not bottom sludge); (5) Pressure vessel: 8 to 24 L membrane vessel reduces pump starts; (6) Control unit: level controller with mains top-up solenoid; (7) Mains top-up device: WRAS-approved airgap (Type AA) float valve assembly with 300 mm air gap - prevents cross-contamination with potable supply (legal requirement under Water Fittings Regulations 1999); (8) Distribution pipework: colour-coded buff/beige per WRAS IGN 9-02-04, labelled 'RAINWATER - NOT DRINKING WATER'.
What is a first-flush diverter and why is it needed?
A first-flush diverter automatically diverts the initial portion of each rain event to drain before allowing roof runoff to enter the storage tank. The first 0.5 to 1.0 mm of rainfall (0.5 to 1.0 L per m2 of roof area) carries the highest load of atmospheric dust, bird droppings, lichen, algae, and moss particles that accumulate on the roof surface between rain events. Without first-flush diversion, this polluted initial runoff enters the tank, degrading water quality (elevated turbidity, E. coli, heavy metals). Device types: (1) Downpipe chamber type: diverts flow into a holding chamber; slow-drain hole in chamber base empties it within 12 to 24 hours ready for next rain event; (2) Ball-float diverter: as chamber fills, ball float rises and seals the chamber outlet, directing subsequent cleaner flow to tank; (3) Continuous bleed: 2 to 5 percent of flow permanently diverted to maintain self-cleaning. BS 8515:2009 requires first-flush diversion as standard; minimum 0.5 L per m2 per event.
How are rainwater harvesting tanks installed underground?
Below-ground polyethylene RWH tank installation: (1) Excavation: minimum 300 mm clearance each side of tank; base preparation - 150 to 200 mm compacted granular sub-base (10 mm gravel or crusher run); (2) Tank placement: crane or excavator; tanks up to 5,000 L can be hand-slid on polythene sheet; (3) Backfill: pea gravel (6 to 10 mm single size) to tank shoulder level - NEVER use compacted clay or crusher run against polyethylene tank walls (overstressing); pea gravel backfill requires no compaction and evenly distributes earth pressure; above shoulder: normal backfill with shallow compaction passes; (4) Traffic loading: specify SLW 30 (pedestrian, light vehicle) or SLW 60 (heavy vehicle) rated tank and extension shaft for driveway/parking installation; (5) High groundwater: if seasonal groundwater within 500 mm of tank base, anti-flotation anchor straps or concrete deadman anchors required (buoyancy of empty 7,000 L tank = 7 tonnes uplift); (6) Commissioning: chlorinate tank (10 mg/L, 30-minute contact time), flush, then fill with rainwater or mains water to test system.
What certifications should rainwater harvesting equipment have?
UK required certifications: (1) WRAS (Water Regulations Advisory Scheme) Approval: all components in contact with water intended for domestic use must be WRAS-approved (or demonstrate compliance with BS 6920 extraction tests for materials); the WRAS Product Approval Scheme lists individually tested products; (2) BS 8515:2009+A1:2013: the UK standard for design, installation, testing, and maintenance of RWH systems - compliance is required under the Water Supply (Water Fittings) Regulations 1999 where installed; (3) For commercial systems: BREEAM Water credit Wat 01 awards credits for RWH system design and performance; (4) CE marking (EN 12566 for tanks in some configurations; EN 858 for separator elements); (5) For below-ground tanks under traffic: EN 1250 structural assessment certificate for relevant load class; (6) NSF/ANSI 61: for US installations, components in contact with potable or potable-adjacent water should meet NSF 61 extraction requirements. German DIN 1989 Parts 1 to 4 is the equivalent comprehensive standard in Germany.
Illustrative scenario · Commercial and light industrial rainwater harvesting equipment supply
A composite drawn from typical projects in this category, not a single client engagement. Figures are indicative.
- Challenge
- A facilities management company procuring equipment for a rainwater harvesting retrofit across five hospital car park buildings in Yorkshire struggled to source components that met NHS Estates WRAS and HTM 04-01 requirements simultaneously, while keeping system cost within the GBP 120,000 budget allocated across all five buildings.
- Approach
- The contractor specified vortex pre-filters with WRAS-approved polyamide housings, below-ground polyethylene tanks with WRAS-approved inlet and overflow fittings, and a central booster set with NSF 61-listed bronze impellers. All pipework fittings were selected from the WRAS product approval database. A calmed inlet assembly and floating suction were specified per BS 8515 to maintain tank water quality without chemical dosing.
- Outcome
- All five systems were installed within budget at GBP 114,200 total. DWI and NHS Estates inspection confirmed WRAS compliance on all wetted components. Combined annual mains water saving of 2,100 m3 was verified against post-installation metering, reducing site water costs by GBP 7,300 per year across the portfolio.
Questions to ask shortlisted providers
5
- 01
Are all wetted components WRAS-approved and listed on the WRAS Product Approval Scheme database?
Non-WRAS components in any system connected to potable supply constitute a breach of the Water Supply (Water Fittings) Regulations 1999; water undertakers can require disconnection.
- 02
What is the pre-filter mesh size and self-cleaning mechanism for the roof collection filter?
Coarse debris removal (280 to 500 micron) before tank entry determines long-term water quality and maintenance frequency; hydraulically self-cleaning vortex filters are preferred over cartridge filters in all but the smallest systems.
- 03
What tank material and structural loading certificate applies (PE, GRP, concrete, traffic loading class)?
Below-ground tanks under vehicular areas must carry EN 1250 traffic load certification; incorrect loading class results in tank deformation and potential collapse.
- 04
What is the mains top-up device type and has its airgap configuration been confirmed as Type AA per WRAS?
The airgap is the only permissible backflow protection method between potable supply and a harvested rainwater system; float valves or solenoid valves that create a submerged inlet are not compliant.
- 05
Does the system include telemetry for yield and demand monitoring and is data exported to the BMS?
Monitoring enables proof of performance for BREEAM credits and identifies pump faults or top-up overreliance before they become compliance issues.
What drives cost in this category
4
- Pre-filter specification and quantity
- Self-cleaning vortex filters cost GBP 180 to 650 per unit; one filter per 100 to 200 m2 of roof is typical; inferior cartridge filters cost less but require frequent manual cleaning.
- Tank volume and installation type
- 3,750 L polyethylene below-ground tanks cost GBP 600 to 950 supply-only; 10,000 L units cost GBP 1,800 to 3,200; GRP bespoke tanks for commercial volumes above 20,000 L cost GBP 120 to 200 per m3.
- Pump set and controls grade
- Single residential pump sets cost GBP 1,200 to 3,500; commercial duty/standby booster sets with frequency control and BMS output cost GBP 8,000 to 35,000.
- WRAS compliance verification and documentation
- Sourcing and documenting WRAS approval for all components adds 3 to 8% to equipment procurement cost but is non-negotiable for legal compliance; non-WRAS components can cost 15 to 30% less but carry regulatory and liability risk.
Key regulations and standards
4
- Water Supply (Water Fittings) Regulations 1999
- All fittings, equipment, and materials in contact with water supplied by a water undertaker must comply with Schedule 2 (fluid category backflow requirements) and be of suitable materials per Regulation 4; WRAS approval is the standard evidence of compliance.
- BS 8515:2023 Rainwater Harvesting Systems
- Code of practice specifying component requirements including filter specifications, tank materials, mains top-up device type, and pipework identification; suppliers should demonstrate compliance against each clause for systems installed under Building Regulations Part G.
- BS 6920 Suitability of Non-Metallic Products in Contact with Water
- Specifies extraction test protocols for materials used in water contact applications; WRAS approval requires BS 6920 test data; specifying non-tested materials risks regulatory non-compliance and potential public health liability.
- CE Marking under EN 12566 (Tanks) and EN 1250 (Traffic Loading)
- Below-ground polyethylene and GRP tanks require CE marking and structural test certificates; tanks installed under driveways or roads require EN 1250 load class certification appropriate to expected vehicle loads (SLW 30 or SLW 60).
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