Nowadays, luckily, we don’t have any problem with water supply in cities and towns, so it is not necessary to storage water in residential dwellings. If you have to have available water reserves and you haven’t yet decided what kind of container you are going to use, it is advisable to use tanks which must never be buried.   What conditions must a rainwater storage tank meet?                                                                                                                             – They have to be built as far as possible from potential polluting areas like landfills, dung-heaps, septic tanks…. – They can be of several materials like concrete, plastic… – They must be completely watertight, without cracks, to avoid water leakage and pollution. – They must have easy access to be able to perform cleaning works and maintenance with no problem. – They will be equipped with a drainage system to be able to eliminate the first rain water, as this always drags earth and dirt which could pollute the water. – Once the roofs and pipes are clean, the water will go directly to the tank. – The tank must have a sand filter before the entrance so that the water which goes to the tank is as clean as possible. – If the tank has ventilation ducts, these will be placed very high so that they will be always over the water level and they will be protected with a tank trap to prevent insects, birds, etc. from entering there. – It must be avoided the lighting to avoid algae proliferation. – The parapet of the tank will have a door or a cover that will fit perfectly and it will be always elevated from the ground level. – The area around the parapet must be steep enough to avoid rain drags. – The water will be extracted by pumps that don’t require be fueling or submerging.   Extrusion welding,  plastic extrusion welding, PVC extrusion welding, PVC extrusion welding, polyethylene rod welder, Leister Fusion, Leister weldplast,   In the following link you could see a video about machines which weld polypropylene sheets for the production of tanks.