RAIN WATER HARVESTING MADE BY: Abhay goyal X-B 754
Rain Water Harvesting?.• Rain Water Harvesting RWH- process of collecting, conveying & storingwater from rainfall in an area – for beneficial use.• Storage – in tanks, reservoirs, underground storage- groundwater• Hydrological Cycle
How? 1.Collect 2.Use 3.Store4.Recharge if there’sexcess
What can we use the rain water for? If used for drinking, it is absolutely necessary to check water quality in a lab and treat as required
RWH – Methodologies• Roof Rain Water Harvesting• Land based Rain Water Harvesting• Watershed based Rain Water harvesting • For Urban & Industrial Environment – • Roof & Land based RWH • Public, Private, Office & Industrial buildings • Pavements, Lawns, Gardens & other open spaces
Rain Water Harvesting– Advantages1.Provides self-sufficiency to water supply2.Reduces the cost for pumping of ground water3.Provides high quality water, soft and low in minerals4.Improves the quality of ground water through dilutionwhen recharged5.Reduces soil erosion & flooding in urban areas6.The rooftop rain water harvesting is less expensive &easy to construct, operate and maintain7. In desert, RWH only relief8. In saline or coastal areas & Islands, rain waterprovides good quality water
WHY Rainwater Harvesting?•To arrest ground water decline and augment groundwater table.•To beneficiate water quality in aquifers.•To conserve surface water runoff during monsoon.•To reduce soil erosion.•To inculcate a culture of water conservation.
Broadly there are two ways of harvesting rainwater: (i) Surface runoff harvesting :- In urban arearainwater flows away as surface runoff. This runoff couldbe caught and used for recharging aquifers by adoptingappropriate methods.(ii) Roof top rainwater harvesting:- It is a systemof catching rainwater where it falls. In rooftop harvesting,the roof becomes the catchments, and the rainwater iscollected from the roof of the house/building. It can eitherbe stored in a tank or diverted to artificial recharge system.This method is less expensive and very effective and ifimplemented properly helps in augmenting the groundwater level of the area
Rooftops are favoured becauseof the large coefficient of run-offgenerated from them andrelatively less likelihood of theircontamination.
The water that leaves the rooftop may be 65 – 90% ofthe water that falls on it Roof material absorbs some water Evaporation losses More water loss if roof is flat
lead the water from the catchmentsurface to the storage tank
FILTER AND FIRST FLUSHDEVICESremove grit, leaves and dirt that therainwater may transport from thecatchment, before the water enters thestorage tank. When it rains after a longgap, the rooftops are usually very dirtyand the rainwater also carries with it a lotof dissolved air pollutants. A first flushdevice diverts the water from the first rainso that it does not enter the storage tank.
Down take pipes Over flow Filters Inlet Gravel Sand Make your own filter with Out flow Storage tank Gravel sand, charcoal and gravel OrFirst flush Filter Recharge tank Buy a filter off the shelf Check and clean filters before and after each rainy season
First flush• The first rain carries with it a lot of filth from the rooftop and dissolved air pollutants• This rainwater should be diverted away from the storage tank using a first flush device.• Some filters have a first flush system integrated in them• Check and clean first flush devices First flush standpipe regularly.
DELIVERY SYSTEMPiping systems that convey the storedrainwater till the point of end-use.It is not recommended to use harvestedrainwater for drinking, cooking anddishwashing unless water quality issues areverified and necessary treatment orpurification systems installed.
From the simplest ground leveltank, surface lined ponds andlarge lakes storage options aremany depending on the context ofthe rainwater harvesting design.
STORAGE• Above ground ▫ Ground level or Intermediate floor level Save on pumping cost ▫ Just below roof• Below ground
Storage tank features• Durable and no leaks• Built on a strong and stable substrate that can support the tank filled with water• Opaque – presence of light can cause algal growth in tank• Secure and impervious cover• Vents to be covered with insect proof mesh• Located as close as possible to demand and supply points to reduce plumbing
Storage tank features• Overflow pipe should be provided close to the top, to reduce dead space.• Overflow pipe diameter should be equal to inlet pipe diameter• Overflow pipe should lead excess water away from the foundation of tank and other buildings. Preferably the overflow should be led into a groundwater recharge system or a garden• There will be sedimentation in the tank. Taps and pipes to draw water from the tank should not be very close to the bottom to prevent sediments from entering the plumbing system and clogging it.
STORAGE SIZE Do a waterDepends on audit to check water requirement.• Rainwater availability• Water requirement• Budget (storage tank is most expensive part of (rwh system)• Available space and aestheticsExcess water can be diverted into a groundwater recharge system
1. Storage of Direct use2. Recharging ground water aquifers3. Recharging of bore wells4. Recharge Pits5. Soak away or Recharge Shafts6. Recharging of dug wells7. Recharge Trenches8. Percolation tanks