Making and Using a Water Level

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Water Level Principle of Operation

For the uninitiated, note that a water level is a very simple device that anyone can make and use. It's principle of operation is very simple: water tends to seek the lowest point possible. Although you can make one simply by buying a length of tubing, there are a couple of enhancements that make the device far easier to use (more below.)

First, take a look at the diagram below (Figure 1). In the water tube, the water is free to flow and will find it's own equilibrium. A moment of thought will prove to you (try it if you don't believe it) that if you anchor one end of the tube and only move the other, that the waterline will always remain at the same point above the Earth. The plastic tube simply moves up and down around a constant water level. The tube can go up and over and around things, and the water level remains constant. That said, note that there are some things that you can get wrong ...the warnings follow the diagram.

Using a water level

Figure 1) Water Level Setup

Using the Water Level

  1. Anchor one end of the tube as shown. The 'anchor' can be a fence post, wall, or any upright structure. The tube height should be similar to the height of the level line that you wish to create
  2. Tape or clamp the tube above and below the waterline so that the tube between the mounts is vertical
  3. To ensure that you are not 'carrying' the tube of water off the ground by accident, make sure that you keep the tube near the anchored upright on the ground. It helps to lay something across it, like a sand bag
  4. Move the other end of the tube around and measure vertically from the waterline to where you intend the level line to be (see images in the Construction section below). The 'level line' that you are marking could be the tops of fence posts, curtain rod ends, or lines on boats. It doesn't matter.

Warnings

  1. Raising both ends of the tube, or raising one end of the tube so high that the tube is lifted off the ground will raise the water level on both ends. Go high enough and you'll overflow water out one end and have to start over. Keep one end on the ground as mentioned above. I prefer the anchored end. Since the volume of water in the line will not change, the water line on both ends will stay the same
  2. Do not move both ends of the water line. This is akin to raising the whole tube up and down. Although small movements of both ends are OK, raising both ends too much will carry the whole tube uphill and raise the water lines on both ends. Lowering both ends is OK. Try things out and see what I mean. The water level remains the same unless you 'carry' the water higher by moving the whole tube uphill.
  3. Use a long tube. In most cases, using a long tube alone will prevent the two errors above.

Building a Water Level

Although you can buy a water level for about the same price that you can build it, note that if you build it that you can add a couple of minor refinements that make it easier to use. In particular, you can use narrower tube in the 'measurement region'. You can add a ball valve on either or both ends. And finally, you can use components that use standard hose thread. See Figure 2 below.

The narrower tube shows more of a movement of water should you be doing anything that causes the water level to change. On the anchored end of the water level, make a mark on the upright so you can track changes and verify that you are on the same 'level' before relying on the other end.

The ball valve on either (or both) ends allows you to lock the flow of water so you can more easily move the movable end around without spilling. I like to have a ball valve on both ends, as I find that sometimes I use one end as an anchor and sometimes I use the other. By closing a valve and putting a thumb over the end of the tube, you can carry your water level tube under and over things that you wouldn't be able to otherwise ...a boon for those working in cramped or odd circumstances such as boat building (crawl under hull, climb up and over, etc). Having a valve in the line gives the tube a natural break where it becomes easy to transition to the smaller 'measurement region' tube mentioned above.

By having standard hose threads on the ball valve gizmo, you can fill the tube from your garden hose and close the valve to keep the water in the tube.

Water Level
(Click to enlarge)

Figure 2) Water Level Construction and Example Usage

In the figure above, the main tube is 5/8" ID and the measurement tube is 3/8" ID. The end of the main tube has a standard hose repair end on it, and the ball valve is a standard type available at most garden stores. The local hardware store should carry the clear tubing. The cost of building the water level is about the same price as buying a quality garden hose ...no big deal considering how useful these things are.

In the figure below, the movable end is actually a short length of MDF that extends beyond the end of the tube. I am shown checking the fore/aft level of a boat hull by crawling underneath (it's upside down) and measuring along longitudinal beams.

Using the Water Level
(Click to enlarge)

Figure 3) Another Example Water Level Usage

Refinements

The amount of movement in the water level, with movement of the movable end of the tube, is equal to the ratio of the surface area of the water on the fixed end to the surface area of the water on the movable end. Why not use this to your advantage? If you are tired of watching the water level bounce around before settling down after each move, try using the coffee can approach. On the anchored end, rather than just mounting the hose as shown, you can run it into the bottom of a can or bucket that you mount instead. Note that you must place the waterlevel in the bucket at a similar level as you would have with just a tube, but just by placing the (full) tube end into the bucket, the fluxuation at the other end will be very greatly minimized. Some people prefer to place one end of the hose into the bucket and then siphon the water through the hose to fill it. Depending on how long your hose is (mine's 24 feet), this could be a bit of a task ...but if you followed my advice on using standard hose thread fittings on the other end, you can still fill the tube with a garden hose prior to putting the end in the bucket (use a clamp). Voila!

That's about it! Go build one and have fun!

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