Water Supply Deficit and a Surgical Ward: Reading the Town's Numbers
A municipal council has population figures of 1,86,000 (2011 census) and 2,34,000 (2021 local count). Its water supply is drawn from a river source with a sanctioned gross withdrawal of 42 MLD; the council supplies water at an average of 135 litres per capita per day at the consumer end, but measured non-revenue water is 28%. Supply is for five hours on alternate days in the older wards and daily in the new colonies. The council has obtained administrative approval for a new 24 MLD source at a capital cost of Rs 96 crore and intends to start construction immediately. Separately, the district administration has asked whether a new 100-bed sub-district hospital should be located in Ward 7 (dense, 41,000 people, 1.8 km from the existing district hospital) or in Ward 14 (newly colonised, 26,000 people, no health facility within 9 km). The chief municipal officer wants a one-page note covering both issues before the next council meeting.
1. Compute the growth rate, the 2031 water demand, and test whether the proposed 24 MLD source closes the gap if losses are brought down to 18%.
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Step 1 - growth. Increase 2011 to 2021 = 2,34,000 - 1,86,000 = 48,000. Decadal growth = 48,000 / 1,86,000 = 25.8%. The implied annual compound rate is about 2.3% ((2.34/1.86)^(1/10) - 1).
Step 2 - 2031 projection. Applying the same decadal rate: 2,34,000 x 1.258 = 2,94,400 (about 2.94 lakh). A geometric projection gives virtually the same figure, which is reassuring.
Step 3 - demand. At 135 lpcd: 2,94,400 x 135 = 3.97 crore litres a day = 39.7 MLD at the consumer end.
Step 4 - gross requirement. With 28% non-revenue water, gross input = 39.7 / 0.72 = 55.2 MLD. Present gross availability is 42 MLD, so the present-day gap is already about 13 MLD.
Step 5 - with loss reduction to 18%. Gross input needed = 39.7 / 0.82 = 48.5 MLD. Adding 24 MLD to 42 MLD gives 66 MLD of capacity - more than adequate, with a reserve of about 17 MLD.
Conclusion. The source alone is oversized if the loss-reduction target is actually met, and the source alone is barely sufficient in the near term because the loss target will take years. The note should therefore reject 'construct first, fix later' and recommend splitting the source into two modules, with the second module released only after measured non-revenue water falls below a trigger value.
2. The council wants to spend the Rs 96 crore on the new source first. Using your numbers, argue the case for a different sequence.
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The arithmetic makes the sequencing argument, not the rhetoric.
The cheapest water is the water already pumped. Closing the gap between 28% and 18% non-revenue water saves 10% of gross input. At a gross demand of 55.2 MLD, that is roughly 5.5 MLD - equivalent to nearly a quarter of the proposed new source, at a fraction of Rs 96 crore. That should be the first tranche.
Second, capacity utilisation. Adding 24 MLD to a 42 MLD system that cannot bill or maintain what it already produces creates a larger asset with the same operating weakness: electricity bills, pump maintenance and pipeline bursts all rise. The new source must be justified by a demand that survives loss reduction, not by a demand inflated by leakage.
Third, phasing. Build the first module (say 12 MLD) with the transmission main and a district metered area programme running in parallel; release the second module when non-revenue water is verified below the trigger for two consecutive quarters. This protects the council from stranded capacity and gives the funding agency a verifiable condition.
Fourth, institutional conditions to attach: metering of all bulk and consumer connections, a published tariff and collection target, an O&M budget ring-fenced before commissioning, and quarterly publication of non-revenue water by ward. Without these, the sanction converts a supply problem into a debt problem.
Present the case as a financing plan with two gates, not as a choice between 'water for people' and 'reform'.
3. Hospital siting: what analysis would you demand before the council commits to Ward 7 or Ward 14, and what are the limits of that analysis?
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What the numbers say, and what they do not. Ward 7 has 41,000 people but sits 1.8 km from the district hospital; Ward 14 has 26,000 people and no facility within 9 km. Population alone favours Ward 7; accessibility favours Ward 14. The deciding variable is therefore unmet demand, not total demand.
Analysis to demand:
- Catchment population within a 30-minute travel time by the modes actually used (walk, bus, auto), not a straight-line radius.
- Existing utilisation data - outpatient footfall and referral load at the district hospital, disaggregated by ward of residence - to see whether Ward 7 is genuinely underserved or merely close.
- Projected population of the newly colonised area over 20 years, since the hospital is a long-life asset and Ward 14 is where growth is occurring.
- Land availability, plot size, access road width, and whether the site floods.
- A transparent weighted score across catchment, access gap, land readiness and future growth, published with the weights.
Limits of a scoring matrix. Weights are a judgement, and small changes in weights can reverse the ranking - so the matrix must not be presented as an objective answer. It cannot capture political legitimacy or the value of a facility that also serves as a referral hub. Ambulance travel time matters more than residential proximity for a 100-bed hospital, which further weakens the Ward 7 case.
Defensible recommendation: Ward 14 if the utilisation data show no access deficit in Ward 7, with a strengthened urban health centre in Ward 7 as the complementary investment.