Data shows that in Nairobi County there are four thousand registered boreholes. Embakasi, Kyuna, Karen, Loresho, Muthaiga, Upper Parklands, Langata and Spring Valley have the highest number of boreholes in the county.
The World Health Organization(WHO) in its guidelines on salt in drinking water – mostly found in borehole water – says that if salt is excessive or above two grams per day, it may be harmful.
The WHO guidelines add that excessive salt intake causes chronic congestive heart failure in humans due to the high sodium levels in the water.
Due to water shortage in Nairobi County, most of the city residents have turned to drinking borehole water and renting apartments that are connected to boreholes which assure of constant water supply.
In September 2020, a team of scientists from Kyoto University in Japan, the University of Eldoret, the African Population and Health Research Centre in Nairobi and the National Taiwan University conducted a study on salty water consumption in the country.
They found that seventy percent of the population had very high salt levels in their urine. Researchers suggested that salty water consumption and other factors like unhealthy dieting could be responsible for the high hypertension cases.
In 2016, the Jomo Kenyatta University of Agriculture and Technology (JKUAT) conducted a study on water samples from Kasarani, Starehe, Embakasi, Langata and Dagoretti. The team reported that the samples had very high salt concentration levels.
Another team from JKUAT published a report on the Journal of Water Resource and Protection that said that all the borehole water in Umoja Inner Core Estate was highly contaminated and therefore unfit for human consumption.
The team had sampled water from hospitals, churches, schools and residential apartments.
Boreholes in Embakasi, Roysambu and Kasarani areas are reported to have salt levels that are above safe limits specified by the Kenya Bureau of Standards (KEBS) and the WHO.
Having access to borehole water is very affordable and reliable but scientists have warned that there is high risk of borehole water being contaminated adding that people should consider factors like heavy metals, pesticide/ herbicide residue and microbial contamination seeping through borehole water.