All the pipes for water supply, sewage and drainage can be installed at two stages:
Pipes are installed when slabs are being casted. This is the method which is very common in builder floors/ villas. In this method, the pipes get buried under the slab or beam or brickwork. In future, if any pipe requires maintenance, it is a problem.
Pipes are installed after structure, brickwork and plaster is completed. This is the method which is the default standard in group housing/ large residential projects, hotels, office complexes etc. In this method, after brickwork is done, pipes are made to stand alongside the wall. This was done so that any future maintenance can be done easily.
Impact of following this method on builder are:
Increase in project duration and cost as scaffolding is required at times to make the pipes stand.
Concealment of pipes is to be done as per design in the front facade or courtyard.