https://www.youtube.com/watch?v=Q-I_bTYvBCA good short video of a water level, showing just a clear house, then a jug with a hose, and then a jug with multi hoses tee'ed together.
if you can find a tri pod (3 legs), with an adjustable rod up/down in center. they can make nice stands for water levels. camera tripods for example. some of the old music stands for sheet music has kinda of a fold-able 3 legs, if you can weld, some rebar could work, with some sort of adjusting butterfly screw on a rod.
get yourself a couple sledge hammers (2 to 4 feet long handle) weight on bottom and a handle that sticks up in air. to help hold ends of water level. with some sort of duck-taped on scrap of wood for a brace so handle does not fall over.
i have taped water level a 2foot x 3foot square before. (( L shape thing with ruler measurements on it, and to check if you have a 90 degree corner or not, along with help ya figure out slope for say cutting lumber and like))
in some odd ball situations... i have ran hose through pipe i was installing. due to wall of house / shed i was not able to go through. and see other side. so i just ran the hose through pipe i was installing. and instantly able to check level-ness / slope i wanted. ((measuring down from water level to see if i had run rise figured out for slope correctly set))
a few times distance was an issue. and the clear hose is rather costly. so i bought a couple garden hose ends and adapters for the clear hose. and installed a garden hose or 2 into the center of the clear hose.
ya water level is a pain dealing with the hose itself. and getting the ends of the clear hose attached easily. so you can move around and place them as needed as you do work. but i think i have seen more 'water levels' than i care to remember. sometimes seeing a jug with clear hose tossed into back of a pickup truck or like at local hardware stores. already knowing someone been using a water level for something.