Poor and weak concrete with inadequate reinforcement in water storage tanks.
Pipes used are of less thickness/ diameter and not of proper grade / make.
Joints in sewer lines not tested.
In some cases, C.I. pipes and specialised corner reinforcement are embedded in lime mortar or cement lime mortar or cement lime mortar or lime concrete. This will result in accelerated corrosion of steel. In these cases, only cement concrete 1:2:4 only should be used.
Some of the points to be noted during execution of water supply works:
Air valves to be provided at high point in the system.
Pressure relief valves to be provided near the discharge ends of pumps and near the sluice valve at the end of a long pipe.
The distance between manholes should not exceed normally 10 mts.
There should be no seepage from the joints and the pressures should not drop by more than 0.2 kg by sq.cm. at the end of one hour.
The discharge of one floor trap should not let into another floor trap.
The pipe from the floor trap to the stack should have a slope of atleast 1 in 5.
To prevent seepage from toilet, bath and kitchen, it should be ensured that the following defects do not occur:
There should be no gap between WC pan and trap.
Floor trap should be fixed properly and should not be constructed.
As preventive measure, the depressed portion should be plastered with 1:3 cement mortars and properly painted with Epoxy resin all-round. Initially, false laying of pipes and WC pan should be done by giving temporary packing. The levels should be checked and corrected considering the final finish level of the flooring. The top of floor trap should not remain much below the floor level. After ensuring this joints shall be done and depressed portion filled up. The shaft walls are to be plastered prior to fixing the stack pipes.