A Simple External Rainwater Tank Gauge.

           Use this calculator to calculate the volume of Rainwater collected in your tank.
.           Enter the amount of rain in mm and the collective Roof area.( Square metres )

Construction:
Obtain a length of clear plastic tubing ( diameter 10 mm ) to configure as per diagram.
Insert into opening at the top of the tank and lower to the bottom then form the desired u bend.
Fill tube with water and drop a coloured float ( anything that is inert and floats on top of the water. ) for easier viewing.
This tube can then be attached to a board which can be graduated.
To calculate the depth of water in your tank just measure the distance from the bottom of the tank to the level shown on your tube.
Enter this data into the calculator and you will get the remaining volume of water in your Tank.
Note: If you do not want to insert plastic tubing into your water tank then use a stainless steel tube which is inserted into the tank to the top of the tank and then attach your plastic tubing.

Another Simple External Rainwater Tank Gauge.

1: Tap   2: T piece  3: To Pump  4: Clear plastic Tube   5: Board which can be graduated
The clear plastic tube should be attached tightly to the T tube with a hose clamp.

If you can not measure the Diameter then measure the Circumference
Click here to calculate the Diameter