Every now and then you need to clean your cistern and I was totally unsure how much mud and sand was in mine. All I knew was that the intake valve was often plugged after non use of my pump and the first bit of water was always dirty. The first year the system had no filter for water from the street so I thought it might be serious but there turned out to be less than an inch of mud. My intake valve is 4-5 inches above the bottom so how it got plugged I don't know.
I drained most of the last 5 inches with a bucket and then we lowered a neighbor in and he finished the job with a sponge, rags and a little cloro. I imagine with double filters the cistern will be good for 3-4 years now.
Entrance under the palapa
Yony inside partially cleaned
I just liked this foto