High Rain, Dry Taps; Need for Rooftop revolution for a Gangtok Water Crisis

Gangtok is renowned for its lush landscapes, cool climate, and steady influx of tourists drawn to its natural beauty. Yet beneath its scenic charm lies a growing crisis ,one that locals suffering with dry taps despite the city receiving abundant rainfall annually.Ironically, while Gangtok is one of the wettest urban centers in India, residents and businesses are frequently hit by severe water shortages. During the dry winter months, the heavy monsoon season, and the annual surge in tourist numbers, the city's already fragile water infrastructure begins to crack, often quite literally.

This year, like many before it, saw critical water supply disruptions. Complaints have poured in from residents across the town. The STNM Hospital ,Sikkim’s largest ,reported a shortage of water for essential services like dialysis. Hotels and homestays, which are key to the local economy, have struggled to meet guest demands, casting a shadow over the city’s tourism sector.Officials from the Public Health and Engineering (PHE) Department and other concerned agencies have been working continuously to tackle the crisis. However, perennial issues like blocked water sources, damaged pipelines, and aging infrastructure have made it difficult to implement long-term solutions. This article attempts to understand the key issue and try to reflect how rooftop rainwater harvesting can minimize upto some extent the water crisis in city.

Is Rateychu Enough?

Gangtok’s urban households rely heavily on a centralized water supply system managed by the Public Health and Engineering Department (PHED). At the heart of this system lies the Rateychu River ,the primary and, at present, the only dependable water source for the city ,located about 16 km away.Water from the Rateychu is treated at the Selep Water Treatment Plant, the city’s sole treatment facility. According to PHED data, the plant supplies approximately 42 million litres per day (MLD) under optimal conditions. However, during the dry winter months, this figure can drop drastically to just 28 MLD ,well below Gangtok’s estimated daily requirement of 30 MLD.Worryingly, water supply from Rateychu has been steadily declining in recent years. Several factors contribute to this drop, including climate variability, reduced spring discharge, and growing anthropogenic pressure on the watershed. Compounding the issue, the monsoon season brings its own set of challenges like landslides and floods frequently damage the aging pipeline infrastructure, disrupting supply to large parts of the city.As Gangtok’s population grows and tourist footfall continues to rise year after year, the strain on the Rateychu source becomes more pronounced. What was once a reliable supply is now proving insufficient, making water shortages a recurring crisis for the state capital.The pressing question remains ,can Gangtok afford to depend on a single source any longer? If it is not , then what can be the possible solution? A rooftop rainwater harvesting maybe.

Rooftop Rainwater Harvesting : reducing water demand and disaster risk

In Gangtok’s current scenario, residents rely entirely on water supplied by the Public Health and Engineering Department (PHED) for all their daily needs ,from drinking and cooking to washing, gardening, and cleaning. However, not all water usage requires the same level of quality. While potable water is essential for consumption and food preparation, many non-drinking purposes can be met with alternative sources.This is where Gangtok’s abundant rainfall presents a practical opportunity. The town receives significant precipitation annually, much of which currently goes untapped. Rooftop rainwater harvesting (RRWH) offers a sustainable way to collect and store rainwater for non-potable uses, thereby reducing the burden on treated municipal water supplies.Beyond meeting daily needs, RRWH has added environmental benefits. By managing runoff and allowing for controlled flow, such systems can help reduce erosion and minimize the risk of landslides in the city’s vulnerable downslope areas ,a recurring hazard during monsoons.

Feasibility in city

Gangtok, one of India’s wettest state capitals, receives annual rainfall exceeding 5,000 mm, with 100 to 184 rainy days per year (sikkimtourism.gov.in). This abundant precipitation offers a vastopportunity for rooftop rainwater harvesting (RWH).A 100 m² rooftop in Gangtok can harvest over 250,000 litres of water annually, while even smaller rooftops can collect 20,000–50,000 litres seasonally. Most urban structures in the city feature sloped tin or concrete roofs, which are ideal for capturing rainfall. Moreover, buildings typically already have downpipes installed for rain runoff, these can be easily connected to storage tanks with minimal scientific modification.RWH systems are cost-effective, require low maintenance, and can be easily retrofitted into existing infrastructure. With basic filtration, the collected rainwater is safe for nearly all domestic uses and can be treated to make it potable.Given the high rainfall, existing infrastructure, and rising demand, rooftop rainwater harvesting is not only feasible for Gangtok but also a practical, sustainable solution to ease the growing pressure on the city’s piped water supply.There are various studies on the feasibility and benefit analysis of rooftop rainwater harvesting by various researcher over various study site confirm that the rainwater harvesting is beneficial to reduce water demand stress and also the recharge of groundwater.

Social acceptance and Government’s role                                      

Numerous studies across different regions of India have confirmed that rooftop rainwater harvesting (RWH) is not only feasible but also highly beneficial in reducing water demand stress and supporting groundwater recharge. In the context of Gangtok, a city that receives exceptionally high rainfall yet faces seasonal water shortages, RWH presents a simple, cost-effective, and sustainable solution. However, the success of such systems depends on both social acceptance and government support. A key concern remains the same: are the citizens of Gangtok willing to adopt rainwater harvesting, or are they still reliant on the conventional piped water system? For many, the idea of transitioning to a new system might seem complex or unnecessary unless they are made aware of the long-term benefits. At the same time, government departments often struggle to reach out and support citizens effectively.

Way Forward

If Gangtok is to avoid repeating its current water crisis in the future, both the public and government must work hand-in-hand. Authorities should take the lead by implementing pilot RWH systems in public buildings ,such as government offices, colleges, and health centers,and use these examples to promote wider adoption. A dedicated policy framework, financial incentives, and technical assistance can encourage individual households to follow system. Awareness campaigns and local capacity-building efforts will further help bridge the gap between policy and practice. With coordinated action, rainwater harvesting can become a vital pillar of Gangtok’s water resilience strategy.

References –

1.      https://savethewater.org/rooftop-rainwater-harvesting-an-ancient-and-sustainable-technique-for-water-management/

2.      https://sikkimtourism.gov.in/Public/Planning/weatherandclimate

3.      gangtokdistrict.nic.in

4.      Barthwal, Sunil, et al. "Socio-economic acceptance of rooftop rainwater harvesting–A case study." Urban water journal 11.3 (2014): 231-239.

5.      Anchan, Sanjith S., and HC Shiva Prasad. "Feasibility of roof top rainwater harvesting potential-A case study of South Indian University." Cleaner Engineering and Technology 4 (2021): 10020 

(The writer is a Research Scholar, Centre for Atmospheric and Climate Sciences, Indian Institute of Technology, Madras, Chennai. Email: yooglesaps@gmail.com)