Gravity Fed Rainwater Harvesting System, 1000-GFT1

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Description

A complete domestic gravity fed rainwater harvesting system with mains water top-up.

This gravity-fed system is specifically designed to supply one toilet with rainwater.

Thanks to its compact-sized header tank and storage tank, this system is ideal for small dwellings where space is of the essence.

It has everything you need to filter, store, and pump rainwater to the point of use (toilet). All you need to supply is the rainwater collection and distribution pipework.

Rainwater storage tank

Our 1,000-litre underground storage tank is complete with a pedestrian rated lid, in-tank-filter, and calmed inlet.

Made from polyethylene (MDPE) plastic.

The storage tank is delivered to site assembled, tested, and ready to install.

 

In-tank rainwater filter

The system is supplied with a 3P Technik  PF in-tank filter, suitable for roof areas up to 200M2

The filter is pre-installed in the tank, where is it joined to the also pre-fitted calming inlet.

This filter removes leaves, grit, and other debris from the incoming water up to approximately 1mm.

Finer particles form a “scum layer” and are washed away during overflow or filtered out by the secondary filtration.

The filter is easy to clean. There are no consumables- just lift, rinse, and replace for continued use.

DAB submersible pump

This system is supplied with a highly reliable DAB Divertron 1000m submersible pump.

It delivers approximately 4 bar of pressure and up to 3,500 litres/hr of flow.

The pump starts and stops automatically by its integrated control system. It has dry run protection, a built-in non-return valve, and a screened filter as standard.

 

Gravity-fed controls

This gravity-fed rainwater harvesting system, also known as an indirect pressure system, uses a header tank that needs to be installed in a location higher than the point of use. In most installations, this will be in the attic space of a building.

The gravity controls have a delayed mains water top-up. The controls and are pre-fitted inside the header tank along with pre-drilled inlets and outlets.

The header tank is delivered to site assembled, tested, and ready to install.

 

How does it work?

Water is pumped to the header tank from the storage tank via the submersible pump.

When demand is placed on the header tank, water is gravity fed to the point of use.

Our header tank has a mechanical mains water top-up delay action.

Should the underground tank become low, the header tank will continue to be depleted until the level has reached the main water top-up level.  At this point, mains water is introduced directly to the header tank.

As the pump is starting and stopping less frequently than with direct pressure systems, the power consumption along with wear and tear of the pump will be much less.

If you require a larger gravity-fed rainwater harvesting system please view our range here.

Tank Specifications

 

  • Capacity litres:  1000
  • Capacity gallons:  220
  • Diameter mm:  1000
  • Height mm:  1500
  • Access entry mm: 600 x 600
  • Weight kg:  110
  • Material: Polyethylene
  • Potable: No

underground rainwater tank installation

Pump Specifications

DAB divetron 1000 m Performance Dimensions

DAB divetron 1000 m pump curve

System Includes

  • Underground storage tank
  • Pedestrian rated tank lid
  • Pre-fitted In-tank calmed inlet
  • Pre-fitted In-tank Filter
  • DAB Divertron 1000m submersible pump
  • Inline strainer assembly
  • Header tank with pre-fitted controls
  • 15 meters of 32mm rainwater pipe
  • Marker tape and ID pack

Specific site conditions should be taken into consideration when designing concrete backfill and should be designed to bear any loads which may be applied during and after installation to prevent the tank from being subjected to these loads.

  • In locations where the excavation will not safely maintain a vertical wall, it will be necessary to shore up the sidewalks of the excavation with a suitable trenching sheet system and bracing to maintain a vertical wall from the bottom to the top of the excavation.
  • DO NOT completely remove the shoring system until the backfill is complete, but before the concrete fully hardens

  • In areas where the water table is above the bottom of the excavation or where the excavation is liable to flood, the excavation should be dewatered using a suitable pumping method.
  • During installation, care must be taken to ensure that the body of the unit is uniformly supported so that ‘point loads’ on the unit are avoided.
  • Excavate a hole of sufficient length and width to accommodate the tank and a minimum of 250mm thickness of concrete surround – and to a depth which allows for the depth of the unit plus concrete base slab and haunch. Also taking into account proposed inlet invert depth.
  • Construct a suitable concrete base slab appropriate to site conditions. Ensure that the slab is flat and level.
  • When the concrete base slab has set enough to support the unit, lay a concrete haunch along the middle of the cast slab to provide even support under the unit.
  • Lower the unit onto the haunch using suitable lifting equipment It is important that the unit is level after installation to allow correct operation of the internal components.
  • Pour approximately 300mm depth of clean water into each chamber of the unit simultaneously. DO NOT OVERFILL.
  • Pour concrete backfill to approximately 300mm depth under and to the sides of the tank ensuring good compaction to remove voids.
  • DO NOT use vibrating pokers.
  • Continue pouring concrete backfill, simultaneously keeping the internal water level nomore than 300mm above the backfill level at all times until the backfill is just below the underside of the outlet connection, leaving sufficient room to connect the inlet and outlet pipework.
  • Connect inlet and outlet drains and vent pipes when safe access to the backfill can be gained.
  • Should you wish to connect in and outlet pipework that is not immediately compatible with the fittings on the unit, proprietary flex seal couplings can be obtained to fit over the outside of the site pipework and the outside of separator connection.
  • Continue backfilling with concrete over the tank body to the required level. Build up a shell of concrete, minimum 250mm thick, around the access shaft(s). Temporarily strut the access shaft to avoid distortion.Vent sockets should be placed as high in the access shaft as possible. Consult with local building control on the exact specification of vent installation. As a minimum, the vent should terminate no less than 2. 4m above the ground, and at least 1m away from any window.Add 250mm to the tank in questions dimensions, this will show calculate your minimum excavation size. Please see the below example installation with the tank with minimum 250mm full concrete surround.

    underground rainwater tank installation
     

Additional Information

The rainwater harvesting system is delivered complete with the components as listed.

All you need to supply is the DN100 pipework from the building’s downspout to the storage tank along with DN100 pipework to connect the storage tanks overflow to the storm drain.

In addition to the DN100 pipework, you will also need to supply the pipework from the inline strainer assembly to the header tank and to the point of use.

If you require further information please contact us.

Commercial Rainwater Harvesting