The area that I live in has been in a drought for a year or more. As such we now have water restrictions on washing the car, watering the garden etc. Initially I set up a drainage hose from the washing machine outlet to containers outside to enable me to collect the waste water so I could water the garden. This process worked fine except for the back breaking work of emptying the waste water (grey water) onto various places in the garden.
The next stage was to develop an automatic system that would distribute the grey water into the garden and have the following features.
1) Filter the water before sending it to the garden.
2) Automatic pump to allow water to be delivered to the high end of the garden.
3) Timer to prevent water stagnating in the tank.
The system uses a wheeled trash bin which is made out of 5mm thick plastic (nice and sturdy). Grey water comes into the top of the bin into a filter. When the bin fills to around 3/4 full, a water level switch triggers the pump controller to turn on the pump sitting at the bottom of the bin. The pump continues to operate until the lower water level switch is triggered.
The pump controller also has some logic built into the program to detect if water is in the bin but not high enough to operate the high water level switch. If this situation occurs, at 10 hour timer is started. If the water stays in the bin for 10 hours the pump will start and empty the bin. This stops the water from stagnating. I also have another timer that detects the run time of the pump. If the pump runs for longer than an hour (without any of the level switches being triggered) then the fault LED will be lit and all pumping will stop. This would indicate that the output pipe is blocked.
Step 1: The Schematic of the Pump Controller.
The pump controller is built around a PICAXE 8m PIC. The reason I chose this particular PIC is that it is programmed in BASIC and is cheap ($4 AUD) and I can't program in C to save myself.
There are 3 float sensor switches used in the project. Two of these float sensor switches detect high and low water levels of the tank. The third sensor detects when the water filter needs a clean.
The controller also drives 3 LED's that are mounted on a remote indicator panel in the laundry that indicates pump running, filter clean required & fault condition.
The transformer I used in the project has a 24VAC tap that I was going to use to power some water solenoids. Any voltage from 12VAC to 18VAC can power the circuit. The voltage regulator doesn't get hot as the PIC only draws a few milliamps. I also use a resistor to reduce the unregulated voltage to the pump relay which may need to be altered depending on the relay voltage.