this is one of the best water wall ideas i have found. really simple and let's kids turn the bottles to direct water different places. also keeps bottle caps to stop water! i am going to try this and use other containers too! would work well on wood too.
Investigation area. Enhanced with brightly coloured water (just using a small squirt of paint!), transparent pipettes, jars, tubes etc. encouraging the children to explore with colour mixing, and allowing them to watch the water travel through the various objects.