Taps run murky as main filter at Selep undergoes repairs

Construction of an additional reservoir underway at Selep water reservoir complex above Gangtok.

ENGINEERS DEPLOY ALTERNATE MEANS TO TREAT RAW WATER; NEW FILTER AND RESERVOIR UNDER CONSTRUCTION TO SUPPLEMENT STORAGE; NEW PIPELINE BEING LAID AS WELL

ANAND OBEROI
GANGTOK, 07 Aug: Gantgtokians would have been wondering why the water was running murky in the taps, sometimes full of silt and by the looks of it, unsuitable for consumption. The reason is that one of the two water purification filters at Selep Tanki has ‘choked’. Although the filter is under repairs, it will still take a few more weeks before it is fully functionally again. Fortunately, this is not the only filter at the Selep Tank, there is another, though smaller, which is fully functional and is being employed for treatment of water before it is forwarded to Gangtok homes.
The filter which is under repairs is the larger one with capacity to filter 20 million litres per day while the other one has a capacity of only 4 million litres per day (mld).
It is also informed that Gangtok and the Selep tank will be incremented with another water filter of capacity 21 mld which is under construction. Besides, a new reservoir is also under construction at the Selep tank for water storage to meet the enhanced needs of water requirements in the capital town.
It may be informed that there are two slow-sand filters that purify the raw water coming directly from the source at Ratey Chu to drinking water which is then supplied to the estimated sixty thousand households in Gangtok. The two purifiers have a capacity to treat 32 million liters per day (MLD) which is then stored in the reservoir at Selep Tank which has a capacity of 36 MLD.
Everyday, 15 lakh litres of drinking water is supplied at a rate of 135 litres per head to Gangtok alone. Now, with the major filter that has a capacity to treat 21 MLD per day not functioning, the entire supply is now being channeled through the only functional filter that only has a capacity to treat 4 MLD per day.
With only one purifying filter, the PHE has no option but to treat the raw water for harmful bacteria (that comes in at 100 cubic meters per hour) at the main supply tank through chlorination, use of alumen and other temporary means that reduces the siltation before the water is supplied to households.
With the lower capacity filter the only one functioning at present it would be expected that there would be shortage of water in Gangtok but the department has managed to maintain consistent supply with the discharge of water stored in the reservoirs.
“There can be health implications if raw water is consumed directly, but we are doing the best to treat the water before it is sent to the reservoir from where the supply lines carry it to the households. There might be some instances when the water could be murky and contain silt; however that does not mean that it has been sent directly from the source. We know that the only functioning filter does not have the capacity to treat the entire supply but we have devised a plan and an alternative in place,” states an official here.
It is also intimated that the general public have nothing to be seriously worried; however some precautions before the water is consumed should be maintained since the water is mostly being treated only for turbulence. Further, the officials inform that work on the restoration of the filter was started around two months back under the total renovation of Selep project estimated at around Rs. 31 crore.
“The work on the filter is in full progress and will be completed within a month since even the back-wash system required to be dismantled first before repairs. We have also started work on another water purification filter that has a capacity of 21 MLD which will also be completed within a year. The delay in the works was because there was no separate funding for the purification system and the same was included in the total renovation package,” stated the official.
In addition, it is also informed that the department has started work on the two main water supply pipe lines from Ratey Chu which were laid in 1973. This as per the officials will be a ‘permanent solution’ for the water supply crisis the capital has to face because of heavy rainfall, landslides and heavy soil erosion up source.
It was also informed that even with PHE manpower working at these trouble spots where pipelines are laid at extremely steep slopes the option of creating a tunnel for the pipelines has also been discussed with the Mines and Geology Department.