Hmm.. I can not help but join this forum.
Going by the trend of discussions here, it seems we are working on a smart home, implementing a Pi. cyrus, is that so? What are the objectives to constrain our scope in this particular forum please?
For the problem of water, i suggest we can have a motion detector such as PIR (Has excellent range and detection angle) as occupancy detector to monitor activities within a room, and a solenoid valve at the tap pipe to choke the water if no activity is observed in the room for more than 1Hour or so.
the motion sensors can also be linked to lighting such that when there is no motion, lights go off in a room (relay actuators). we can also have some special sockets connected to this system, so that they can hold appliances such as TV, room heaters, computers, DVD players, Home theatres, and such gadgets that need someone to be present when in operation, and can be easily left ON and silently draw alot of power unnecessarily. This system can be handy in auto switching them off when no one is inhouse, Saving alot of electrical and water bills
we may have also some bluetooth module to interface the system to link with a smartphone app that can be used as the user interface for display and control.
of course the links between all the smart sensors and actuators can be wireless if distances are long. we can think of low cost RF modules that can implement networking eg NRF24L01
- Temperature sensor & smoke detector (Fire detection)
- PIR (Room Occupancy detection)
-Nanny cam (Videos and pictures)
- Relays (for sockets, lamps)
- Solenoid valve (For water pipes)
-Bluetooth modlule ( System to custom phone app for user interface)
-RF modules (Mesh networking between sensors, actuators and the Data acquisition point)
-WIFI module (streaming nanny cam videos and pictures over internet)