Goundwater level measurements underpin most, if not all, hydrogeological studies. While the advent of automatic pressure transducers may give the impression that manual measurements have become less important, this is not the case. They provide much-needed reference data (Rau et al., 2019) and pressure transducers are not generally affordable for everyone. Hence, many measurements are still conducted manually. Most of them are carried out with electric water level tapes (also known as dip meters; Rau et al., 2019). The principle of these tapes is that an electrical circuit is completed at the probe tip upon water contact, triggering a visible and/or audible signal at the tape reel (at ground surface). Despite the simplicity of this concept, these devices often cost several hundred Euros and are not readily available in some parts of the world. A number of textbooks and blogs provide circuit diagrams and build guides (Brassington, 2007; McGill, 2016), but home-made constructions are somewhat hampered by the fact that measuring tapes with integrated wires are difficult to reproduce.
