Water Level Indicator

This weekend we cleaned our tank, but I also invented and installed a water meter. I had this idea cooking around in my head. We have 3 water tanks to our house, so we've never run out of water, but it hasn't rained in weeks and I took a risk cleaning a tank, because it meant losing some water. Since I'm on the volunteer fire team, I was able to use some of our water equipment to pump and store our good water into one of our three tanks. This tank is our main tank. (Technically we have 4 if you count the gravity feed hot water tank on the roof). Sparing you the details, they're all rain water tanks, and they are positioned in multiple areas to store rain water. They equalize to each other's levels. The tank we cleaned takes the brunt of the dirt from the roof (put there by passing vehicles on the dirt road stirring up dust).

Then the water distributes evenly to the other tanks. Our best tank is our new (3 years old) tuffa tank because it's not metal and doesn't have rust.

BUT, we have no way of knowing our water level, nor how much we use in a day or a week, unless we go out and tap the metal tank to see/hear/feel where the water is. Now we do.

Need:
-fishing line
-coffee mug
-empty plastic coke bottle
-metal weights (like washers or something)
-hose clamp
-old piece of pvc pipe

I'm rather proud of this invention, I came up with it when looking at the 'pay' water meters which gave you a REVERSE level. The indicator on the side of the tank would RISE when your water lowered.

Drill a small hole in the top of the tank, put your old pvc pipe in there,if your hole isn't tight enough use the hose clamp to keep it from slipping in, Tie the fishing line to the empty coke bottle, this is your float. Drop it in the water. Run the other end through the handle of your old coffee mug. This is your pulley, drop the mug slowly into the water. It shouldn't move much once it settles. Run the other end up through the tubing and over the side. Eyeball your water level, and tie pull the tension in the fishing line taut. Then tie the fishing line to the weights right at the water level.

The weights will rise with your water level and sink with your water level. So far, so good, the mug hasn't moved, the line hasn't twisted. And now we know that after 2 days of no rain, our tank levels collectively go down about 3 inches.

The best part about this indicator is we can view it from our kitchen window.

I'm a simple man, being able to device simple things that are helpful and work, make me happy.