KWSB official claims chlorine gas evaporates, senior engineers disagree
A new Karachi Water and Sewerage Board report on water quality has revealed that 70 percent of its pumping stations are supplying water containing either low or no chlorine, which is a defense from Naegleria Fowleri, a brain-eating amoeba that swiftly kills and has claimed two lives recently in the city.
KWSB took samples from all its pumping stations after the Sindh Directorate of General Health Services recommended checking how the water is being chlorinated and if the levels at all major water reservoirs were meeting WHO standards.
A second person was killed by Naegleria Fowleri this year on June 2.
The findings were submitted to the World Bank-initiated Karachi Water Sewerage Service Improvement Project (KWSSIP). It emerged that 87 out of Karachi’s 123 pumping stations were supplying water with low or no chlorine.
The samples were collected from hydrants, the two functional Dumlottee wells, reservoirs at Kidney Hill and University Road and all the pumping stations.
The report, a copy of which was acquired by Samaa Digital, says that six pumping stations supplying water through the Kidney Hill pipelines, seven connected with the Low Service Reservoir (LSR) system and 10 other stations connected with the Dumlotee Conduit were sending out supplies with low or no chlorine.
Furthermore, 23 pumping stations that receive water from Haleji Lake through the Gharo Filter Plant, nine pumping stations linked with Hub FP and Hub/COD FP, fourteen connected with COD FP, three each from Pipri FP and NEK-old FP and two pumping stations attached with NEK-II are doing the same.
Chlorine is a gas and chlorination is the process of mixing it with water with machinery called chlorinators. This forms concentrated solution. This solution is then added to water reservoirs to kill the bacteria.
Water is chlorinated to kill parasites, bacteria and viruses. Using or drinking chlorinated water does not harm your health.
“As per the WHO guidelines, water reaching a consumer must contain 0.5 Parts Per Million (PPM) chlorine to avoid waterborne diseases,” a KWSB official told Samaa Digital.
The official, who did not want to be name because of the explosive nature of the report, said that 33 out 87 pumping stations (38%) that were supplying water with low or no chlorine were fed from the conduits, which are open to the sky water channels.
This official claimed that the chlorine gas evaporates into the air and that is why the water that reaches households in Karachi has such low or non-existent levels.
“For instance, 25 million gallons a day out of the total supply to Karachi is from Haleji Conduit,” he said. The pumping station at Gharo (nearly 50km away from Karachi) has a chlorinator. “When water in the conduit reaches Karachi after covering a distance of 50 kilometres, the chlorine evaporates.”
The official added that 53 pumping station that were found supplying inadequately chlorinated water were supplied from six filtration plants. So the problem is also low chlorination at the source.
“KWSB is adding 2PPM of chlorine at all filtration plants, but it disappears in the system before reaching at the consumer,” the official maintained.
The official also attributed the problem to low pressure. Chlorine gas added to water needs 40 PSI to 100 PSI pressure but, the official claimed KWSB cannot maintain the pressure and the chlorine disappears in the system.
These claims are disputed by Jawed Shamim, who served as KWSB chief engineer and has since retired to work in the private sector. Shamim is well familiar with Karachi’s water supply system as he worked as an engineer in many areas. He was also in charge of the KW&SB reform unit at one point before retirement and today works with senior engineers who built K-III. When SAMAA Digital asked him about these explanations, he rejected the claims of the KWSB official and apprehended that what is happening is that the necessary amounts of chlorine are not added at source.
Shamim said KWSB needs to add a minimum 2PPM and maximum of 5PPM of chlorine to its water reservoirs, in line with WHO standards, so that when the water finally reaches a consumer it contains 0.5PPM.
According to him, only 30MGD to 32MGD of water out of a total of 650MGD is supplied through conduits and the remaining quantity is supplied after filtration from KWSB’s six filter plants.
He said 25MGD to 30MGD water is supplied through the Haleji conduit while 5MGD to 7MGD is supplied through Dumlottee’s conduit and nearly 600MGD is supplied through pipelines.
Shamim said that it is true that chlorine evaporates into the air if water is supplied through an open conduit but this does not mean that the entire quantity of chlorine evaporates. He also rejected the official’s claim that chlorine disappears in the system if the pipeline does not maintain pressure of 40PSI to 100PSI.
Instead, he said, once chlorine is added to the water then it cannot disappear for up to 110 hours. “This is true that Karachi receives water from sources that are far away from the city, but it doesn’t mean that it takes days to reach the consumer,” Shamim said. “If water travels from Keenjhar Lake then it may take 16 to 18 hours to reach Karachi and if the supply is made through pumping stations then it may take four to five hours to reach the consumer end.”
To him, there is “no reality” in the claims made by the KWSB official. Shamim was inclined to believe that what is actually happening is that not enough chlorine is added in the first place.
Jawed Shamim’s stand was supported by the University of Karachi’s Assistant Professor of Chemistry Dr Mohsin Ali. He said that a small quantity of chlorine may evaporate or disappear during the supply but it is not true that it would evaporate or disappear entirely.
“KWSB should calculate that how much chlorine evaporates or disappears before reaching the end then it should increase the quantity in its reservoirs.”