Bunyip Water Level

Bunyip Water Level DIY Build

DIY Build: Bunyip Water Level

What is a water level? I guess first before going into that we need to understand a few things about water.

Water finds it’s own level.

If you think about the edge of a calm lake. It’s like a big bowl. All the way around the lake where the waters edge meets land is level. That is a contour line. If you find a way to mark that line, then drain the lake that marked line would be a level contour line in the landscape.

Bunyip Water Level
Water finds it’s own level. The edges of a lake are all the same level. They form a contour line.

This physical nature of water gives us a useful tool in finding level lines in landscape. All we have to do is build a tool to harness the water in a way that we can easily measure the differences.

Bunyip Water Level
If the lake is contained in a tube, the water will still be level on both side.

This is exactly what the Bunyip Water Level does. The hose that is attached to the two measuring sticks is the “lake”. We get to see two sides of the lake against a yard stick. This allows us to accurately calculate the differences between two points.

We aren’t measuring the difference of water levels, we are using the constant level nature of water to measure the elevation differences of the sticks that the water hose tubing is attached too.

As long as we take caution to attach our yard sticks at the same point on each pole, we can use them to see the difference between two points on the ground.

You can click on the images below to get a larger image. Each image has a short description of the parts and steps.

Why use Bunyip Water Level?

I’m going to use the example of a Permaculture swale to answer that question.  A swale is a level ditch designed to slow water down and soak it into the landscape. Water is slowest and most passive when it is allowed to settle into a level area.

Digging a level ditch is most easy when you start by finding level ground. The line that is created by locating individual level points is called a contour line. Don’t get scared by that term. It’s simply a level line in the landscape.

Remember in the lake illustration above we had a line around the lake illustrated by the water line. What if the lake lost enough water for the water line to drop 10 feet vertically? The water is still level and the new line around the edge is simply another contour line.

I may not have made that perfectly clear. There are lots of resources for understanding contours and swales.  Jess over at 104homestead.com has a great post that explains very well.  The author of her post is using an A-Frame level but the concepts of the contour and swale are the same.

How to use a Bunyip Water Level.

This is a two person job. Well, at least with most Bunyip Water Level designs it is. One person holds one pole steady and upright (if it is not vertical the measurements will be inaccurate). The second person will go to the desired distance from the first pole and move around until they find another point that shows the same level measured on the yard stick.

Bunyip Water Level
The porch that these two measuring poles are sitting on is level. The bottoms of the poles are level so the water is level on both ends.

For me, with this Bunyip Water Level, level is indicated at 12 inches. This is just where this level is calibrated. I could add or subtract water to make that number different.

The volume of water doesn’t change inside the tube so as one side goes up the other goes down. Once the water settles down and finds it’s own level again you can take the difference between the two numbers to know how much off level you are. Ideally, when creating swales, you are looking to have the same number on each pole every time. In the case of this particular level that would be at 12 inches on the yellow (top) yard stick.

Bunyip Water Level
The water level will remain the same. Use the measurements on the yard sticks to find the difference of the two marks. This will indicate how far off level you are. If you are working on a swale you want these numbers to be the same which indicates level ground.

Bubbles Equals Troubles: Get The Bubbles Out.

Bubbles in the tubing will lead to inaccurate level readings. You have to take the time to remove the bubbles. I found that this isn’t as easy as I thought it would be.

Place the two measuring poles upright and lay the tubing out along the ground. If you can remove the curling affect of the hose it works out a lot better. Get that hose tubing to lay as flat as possible. Ideally the two poles will be elevated so the bubbles will gradually work up and out. Check your fill level after removing bubbles, and check for bubbles after each fill.

Why Use A Valve?

Did you notice that I installed a valve at the end of each hose? Did you wonder why?

Bunyip Water Level
Once the hose was filled I installed the second Drain Cock valve.

The Bunyip Water Level can be used without a valve. In fact this makes it simpler and cheaper. I installed a valve so that I could lay the poles on the ground if I need too. As long as the valves are closed the water will not spill out. This also makes it easier to transport since you don’t have to worry about losing water. The valves need to be open for operation. The air needs to equalize on both sides and this will not happen if the valves are closed.

Check out this amazing PDF by Brad Lancaster at http://www.harvestingrainwater.com/ for more detailed information on the Bunyip and the A-Frame levels.


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