We just completed our deepest borehole after second attempt: 30 m deep !!!!!
After various unsuccessful attempts with local drillers (6 boreholes from 10 to 18 m !!), Mr Ngumbata contacted MSABI last march to ask us to drill a borehole on his land. We sent a team and drilled 22 m without major problems. Assuming by experience + by looking at the samples that there was a lot of water, we installed the pipes + gravel pack + sanitary seal. We then performed pumptest and much to our surprise and disappointment, had to admit that we couldn’t get more than 250l / hour.
We agreed with the owner to take a two weeks break and decided to try again, deeper this time. The drillers worked during 10 days and managed to reach 30m. The tools got quite heavy to lift in the end and we broke 2 wooden poles (in the end Mr Ngumbata got us one in ebony from his garden!).
There was a lot of tension at the time of entering the pipes and putting the gravel, but the pump test later showed a lot of water. We have just installed the rope today and water is getting cleaner and cleaner. This is our deepest installation so far and we also upgraded it to an hybrid waterwell, allowing further use of electric pumps !