This water meter is the most accurate level meter I have ever used (not counting micrometers or calipers).
It is easier to use and more accurate than using a bubble level and line, or tape measure. It can be done by ONE person, It can be used around corners from your reference point. I have used it to redo my entire perimeter drain system on my house and redo my back concrete patio to ensure slope and proper drainage, as well as level the pier blocks for my patio and shed to ensure they are all level.
It is CHEAP to build! It is SUPER ACCURATE! It is FAST to use!!
I searched the internet and specialty tool shops around my area and found similar but inferior products available for in excess of $100.
Here is a site that not only sells them but offers great explanations on how to use them.
I preferred building my own as it was a lot cheaper, and I had most of the materials already on hand.http://watrlevel.com/index.htm
This cost me $15 for the tubing and ruler but has saved me thousands in man hours!!!!!