The old drama of water wearing away stone makes a pleasing yin-yang water feature on your patio or in the garden. If the stone is drilled so that water can burble out of it, the effect is magical. You can drill holes in stone yourself with the right tools and goggles. You can also buy drilled boulders and rocks from stonemasons and quarries that supply nurseries and landscapers -- or you can find an old stone that is already drilled.
Drill a hole straight up through a craggy rock or a boulder, making a tunnel large enough in diameter to hold a length of PVC pipe. Set the boulder over the pipe, on a rock pile in a small pond. Hide a pump in the rock pile, connected to the PVC pipe and protected by a wire cage. The pump should send water up through the boulder to shoot or spill out the top and cascade back into the pond. The pond can hold fish and plants if it is deep enough and if the pump is powerful enough to run a filtering system as well as the fountain.
Stacked Stone Fountain
Drill holes carefully through the centre of a stack of large decorative flattish stones. Then stack them one on top of the other around a metal pipe cut to end 1/4 inch below the rim of the hole in the top stone. Stabilise the pile with small slivers of stone used as shims. Hold it in place with clear silicone glue. Set the stone stack over a hidden water basin that holds the pump, which pushes water up the pipe to bubble out the top of the stones and cascade down the sides.
Polished Boulder Basins
A small boulder, cut in half, hollowed out and polished, is a beautiful and humble basin for water. Let a bamboo delivery spout, connected to a hidden pump and reservoir, fill the boulder basin with water. The water tumbles over the edge of the basin, through a base of river rocks and into a buried water trough. Or drill a hole through the centre of the boulder, in the middle of the basin, and let the water enter the boulder bowl directly, without the external spout. This is a pretty water feature when it is surrounded by containers of running bamboo or a modest grove of clumping bamboo.
Half the work is done for you if you can find an old millstone for an entryway. The stones were used in 19th-century mills and so they come with a hole predrilled in the middle. If you have a very large millstone, set it on a sturdy base in an old industrial cauldron, where you have plenty of room to hide the pump. Set the base under water so only the millstone shows. Fasten the water hose or pipe to the hole in the millstone --- if it is a nice, verdigris copper pipe, let it stick up a bit. If it is an ugly plastic hose, attach it just out of view inside the centre hole. A small millstone or grinding stone could sit in a recycled fire pit with the pump hidden in the pit. Or the millstone can sit right on the ground --- over a hidden reservoir that holds the water and the pump and is disguised by rocks over a sturdy mesh screen.