Feasibility study for installing greywater recycling solution at a tribal hostel

JalSevak Solutions present a feasibility study for implementation of JalSevak greywater recycling system at a tribal students’ hostel in rural Maharashtra. We analyze the present conditions, existing water supply infrastructure, possible design of the greywater recycling solution and potential benefits.

Background

Vanavasi Kalyan Ashram, Maharashtra (वनवासी कल्याण आश्रम, महाराष्ट्र) is a non-profit NGO working for the welfare of Tribal people of Maharashtra. It especially focuses on providing education to the Tribal students and also runs several hostels across the state and country. Boys and girls belonging to Nomadic Tribes (Adivasis) are accepted and accommodated in these hostels. One such hostel is located at a settlement called Chinchavali, 12 km from Panvel and 50 km from Mumbai. As of August 2016, 36 tribal students of ages ranging from 10-16 reside in the hostel along with 4 support staff.

VKA hostel
Figure 1 – Hostel building

Present water situation

Though only 12 km away from Panvel city, Chinchavali area suffers from chronic water shortage. A seasonal river flows nearby during the Monsoon and runs completely dry by December. The only source of water for the community is a well run by the Gram Panchayat that distributes this water to its residents. The well has good amount of water during and after the annual monsoon. By December of every year, however, the well water level starts declining. From December till the June of next year, residents have to either rely on borewells (which too run dry) or costly water tankers.

Current water consumption at hostel

VKA consumption
Figure 3 – Break-up of water consumption

During monsoon period, the hostel receives ~ 2500 litres per day of water supply. At 62.5 litres per day per capita, this water supply is less than half of the 135 lpd suggested by Indian standard 1172. A quick breakup of water consumption activities is given. Most important activities include:

  1. Cooking and drinking: 42% or 1050 litres
  2. Bathing and clothes washing: 26% or 650 litres (there is no washing machine in the facility and the students wash their clothes by hand)
  3. Utensil cleaning: 14% or 350 litres
  4. Toilet flushing: 18% or 450 litres

Needless to mention, this breakup indicates that sufficient water for toilet flushing is not available. Moreover, since this is the best case scenario of water supply (2500 litres per day), water consumption on toilet flushing activity is expected to reduce from 18% to less than 10% during summer months. This results in severe lack of sanitation and well-being of the students.

Current layout of toilets and bathrooms

There are 4 bathrooms, 4 toilets and 4 washing sinks at the hostel. See pictures below. The toilets are of Indian-style and there are no flush tanks. Water is poured manually after use which results in inconsistent cleanliness and hygiene.

Figure 4 - a) Present arrangement of bathrooms and toilets on the campus; b) Indian-styled toilets with no flush tanks.
Figure 4 – a) Present arrangement of bathrooms and toilets on the campus; b) Indian-styled toilets with no flush tanks.

 Discharge from all 4 bathrooms and sinks is not connected to sewage line and discharged into open space behind the bathrooms. This leads to long term hazards from sewage.

Figure 5 - Backside of the bathrooms showing discharge pipes dumping water into backyard.
Figure 5 – Backside of the bathrooms showing discharge pipes dumping water into backyard.

Greywater estimates

From the breakup shown in Figure 3, daily greywater production is estimated to be roughly 1000 litres (bathrooms + utensils washing). This greywater that is discharged into open, can be collected and reused for toilet flushing. 18 per cent fresh water that is currently used for toilet flushing shall be potentially saved. Schematic layouts of current practice and proposed solution are given in Figure 6 and Figure 7 respectively.

Current layout
Figure 6 – Schematic layout of existing water distribution
Proposed layout
Figure 7 – Schematic layout of proposed water distribution

 

Potential benefits of implementing greywater system

Channeling the greywater back for toilet flushing shall offer following significant benefits.

  • 18% savings (450 litres/day) in freshwater
  • Double amount of water available for toilet flushing (from 450 litres/day to 1000 litres/day)
  • Reduction in open drainage (1000 litres/day)

Additional benefits of implementing such system are:

  • Significantly improve sanitation and well-being
  • Improve resilience against water shortage
  • Potential for increase in number of students due to availability of water
  • Additional water available for gardening, agriculture

Project Cost

This project shall require refitting all 4 toilets with western-style commodes for better cleanliness and hygiene. Plumbing modifications are easy and shall not require replacing any pipes. Table 1 gives a high-level costing for installation of JalSevak greywater recycling system and Table 2 gives approximate operating cost.

Table 1 – System installation cost

Item Cost
Western-style commodes in all 4 toilets ₹ 10,000
Plumbing to collect greywater ₹ 30,000
1500 litre capacity JalSevak greywater system
Plumbing to connect 4 flush tanks

Table 2 – System operating cost

Item Cost
Sanitizer refill ₹ 5 per day
Electricity 1 kWh per day

Economic Impact

As mentioned previously, the hostel has to survive on water tankers for 5-6 months in a year. A water tanker of 10,000 litre capacity costs approximately ₹ 2,000 making the water cost to be 20 paise/litre. Conserving 500 litres of fresh water per day would result in a saving of ₹ 100 per day. Subtracting ₹ 10 per day as operating cost, the net daily saving for the hostel is ₹ 90 which is ₹ 32,500 per annum. With the total system cost at ₹ 40,000, the simple payback period is 1 year 4 months assuming a full year on tanker water supply. So in reality the payback would be 2 years 8 months (since tankers are needed for only 6 months per year). To summarize:

  • Daily water savings: 500 litres
  • Daily water cost savings: ₹ 90
  • Monthly savings: ₹ 2,700
  • Simple payback period: 2 years 8 months

Sanitation Impact

  • Cleanliness shall be improved by 100%
  • Open sewage shall be reduced by 100%

CONCLUSIONS

We have conducted a feasibility study of installing JalSevak greywater solution at a tribal hostel in Maharashtra. The study shows that reusing bathroom and sink water for flushing and cleaning toilets results in significant impact on fresh water conservation (500 litres/day), sanitation improvement (by 100%) and reduction in open sewage (by 100%). The modifications involve refitting all toilets with western style commodes having flush tanks. A total cost of ₹ 40,000 is envisaged and return on investment is estimated as 2 years and 8 months. Besides the economics, well-being of these underprivileged children can also be significantly improved.

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