- Rain Water System and Grey Water System at 281 Redcatch Road.
- (Also with a note on Solar Panels.)
- General plans and implications for Architects and Builders while the
building is being extended.
- The proposed Rain Water System (RWS)
- The aim is to not let any rainwater from roofs or from the ground surface
(e.g. car port or drive and the patio) to enter the town drains, not even rain
from a cloudburst or exceptional rainfall over a period of time. The Water Co
give a small reward for this, but the motivation is 'Green'.
- All rain onto our roofs is to be routed to a collection point near the
south corner of the new extension (i.e. near the shed, which I shall call the
- The collected rainwater will be stored in one or more large butts near the
- Rainwater downpipes from roof gutters are to go to water tubs or butts, (c
100 to 200 litre) one in front, one at back of house. Will need mains
connection. Will need pipe to outlet near South Shed.
- The stored rainwater will be used mainly for:
- a. augmenting the Grey Water System, i.e. to be used in the WCs in the
- b. replenishing the ornamental pond.
- c. watering the garden.
- OVERFLOW and surface run-off.
- The original plan was (and I hope may continue to be) that overflow from
the collection system (and surface run-off) is routed onto the lawns. Both the
lawns, the one at the front of the house and that at the back, have been
landscaped such that excess water would be trapped on the lawn to a depth of
about 10cm. The front lawn is approx xxx square metres, The back lawn is
approx yyyy square metres. Thus each will hold up to zzz cu metres. The roof
area will be approx Sq Metres so each mm of rain will produce cu metres of
water. The average rainfall in xxx the month with the heaviest rainfall on
average is mm.
- The plan was to observe the effects of unusually high rainfall and if
necessary construct one or more standard 1 cu metre soakaways to augment the
soakaway effect of the front and back lawns and flower beds.
- However a recent pamphlet from the Water Company suggests that all rain
must be routed to standard soakaways, not to rain water butts. If this is the
case this rule is hard to understand. A later version of this document will
clarify the situation.
- SURFACE WATER
- The car parking space at the front of the house is currently mostly
permeable and it will eventually (on completion of the building works) be
entirely paved with permeable materials. At present the concrete part of it
drains into the permeable part. In the future any run-off will be routed to
the front lawn. There will be a grating-covered gully along the boundary of
the property and the highway, with water routed onto the front garden.
- The patio at the back of the house also consists of permeable brick and
slopes such as to route run-off onto flower beds. Any extension of this patio
will keep to this scheme.
- In the two years since this patio was installed we have never observed
surface water more than approx 2 mm deep and it has never been seen to persist
form more than half an hour.
- Grey Water System (GWS)
- The purpose of the GWS is to re-use some household waste water that would
normally go into the town drains. The water will be processed then stored for
use to flush the WCs and will also be available for watering the garden.
- Collection. In the kitchen a second sink normally used for rinsing will
have its drain routed to the GWS.
- Baths, showers and wash basin will also be routed to the GWS.
- House rules will attempt to ensure that very dirty water, or excessively
soap-laden water, will not be put into these drains.
- Bathroom users will be asked to pour particularly dirty or soapy water
into the W.C.
- Technology for collection..
- The drain from each appliance (wash basin, shower etc) will go to a lidded
trap either (preferably) just above floor level in the Utility room, or just
below ground level either in the floor of the utility room or outside.
Capacity 5 to 10 litres.
- In the trap there will be a submersible automatic pump, or submersible
pump and a water level sensor. Probably mains powered, so a suitable wall
connection will be required. The pump capacity should in the range 10 to 20
litres per minute. If and when the pump cannot pump all the water coming in,
the water overflows to the town drain. The pump output will be routed to the
grey water system processing near the South Shed.
- Use of Grey water.
- The normal WC supply cisterns will be fed from an additional cistern (the
"GW cistern") located in the roof space.
- The GW cistern will normally be fed with water from the GWS storage tank
by a pump near the storage tank, which will be actuated by a sensor near the
top of the GW cistern.
- In case the GWS fails to provide sufficient water the GW cistern will also
have a supply of mains water via a ball-cock located near the bottom of the GW
cistern. Initially this will be the only source of water for the WC cisterns.
- Overflow from the GW cistern will be to the exterior, in such a place as
to attract attention. (e.g. onto the front door porch!)
- I am hoping that Paul can construct the trap and the GW cistern, including
provision of the sensors and suitable ball-cock. (I am assuming these devices
are not readily or cheaply available. ??)
- It would be good if a suitably qualified person could check my estimates
of capacity of stores and pumps.
- SUMMARY of MATTERS CONCERNING ARCHITECTS AND BUILDERS
- I hope the necessary infrastructure can be incorporated into the work on
- It would be helpful if Henry could estimate the additional cost of the RWS
and GWS in case we decide to fund these installations from a different
- As far as the current building work is concerned I would hope:
- 1. That for the RWS, we install and re-install the roof gutters so as to
bring all the rainwater to two downpipes, one at the front, one at the back of
the house with pipework installed from these butts to near the South Shed.
Electric power outlets will need to be provided near the butts, to power the
submersible pumps which will be installed in each butt.
- 2. That we install pipework from all washbasins, baths, and showers and
the rinsing sink in the kitchen to the sump in the Utilitiy Room (or to one
- 3 . That we install pipes :
- a. to carry the collected waste water from the sump to a point in front of
the South Shed
- b. to carry cleaned grey water from near the shed to the GWS cistern in
the roof space.
- (The GWS processing/cleaning equipment will later be installed near and
behind the shed.)
- 4. That we install the GW cistern with its mains water supply in the roof
space. (The GWS cistern will be supplied by me, probably constructed by Paul).
And the pipework to feed the WC cisterns from the GW cistern.
- The connections beween the house and the RWS/GWS equipment near the south
Shed could be via a channel with a removable cover across the side access path
at the side of the house, for these pipes and for power and control wiring.
Alternitavely they could be underground, in which case more cables and pipes
than specified here should be included so as to allow for future developments.
- Summary of pipes etc. across footpath, i.e. to and from house and South
- Rainwater collection pipes (2)
- Grey water collection pipe
- Grey water supply to roof space
- Wires to Sensor in GW cistern
- Power for the the GWS pump (and for the South Shed)
- Extensive use of in-pipe stop cocks to facilitate later modifications.
- SOLAR PANELS
- 1. Water heating
- The currently installed hot water solar panels will need to be moved to
the new roof.
- 1. a. . I am working on a plan to add a heat dump, in order to stop the
water reaching boiling point, which has several disadvantages. This would
involve additional pipework and control.
- 2. Electricity Generation.
- I intend at a later date to install PV panels to generate electricity.
Currently I have no detailed plans. But we need to aim to maximise the amount
of roof area facing in a southerly direction.
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