All salt based water softeners have a discharge pipe.
They work by:
- having a pressurised tank that is full of volcanic rock.
- your incoming hard water passes over the volcanic rock and then leaves as soft water to go into your house.
- the 'hard' part of your water, 'calcium carbonate', is removed by it sticking to the surface of the volcanic rock making the water 'soft'.
- the volcanic rock gets layers of calcium carbonate on it making it less effective to remove the calcium carbonate.
- The water softener also has a tank of brine, 'salty water'.
- At programmed intervals the water softer turns off the water that leaves the water softener into your house, and opens a value from the water softener into the discharge pipe.
- The water softer then adds the brine to the incoming water and washes this brine over the volcanic rock and out into the discharge pipe and out to a drain.
- The salty water washes the calcium carbonate off the volcanic rock to restore it and make it effective again.
.- This can take 30min so uses a lot of incoming water that goes out to the drain.
- At the end of the cleaning cycle the water softer stops using the brine, stops the incoming water, closes the value from the water softener into the discharge pipe. and re-opens the valve from the water softener into your house.
- and the incoming water once again passes over the newly cleaned volcanic rock on its way into your house.
Good water softeners check to see how much water you are using and do this wash process only when need (expect every 3-7 or so days) and normally at night.
ps I have found that buying salt in bulk (250kg for more than 2 years) is cheapest from a local salt bulk supplier
eg:
http://www.clarksaltsupplies.co.uk/
SFK