Backyard Stream

At my wife’s urging I/we decided to re-landscape the backyard. The yard is a side slope and the original landscaping was a small lawn, a concrete retaining wall, a series of brick terraces and a brick stairway. But the brick walls were leaning and collapsing, the stairway was straight and ugly, and I wanted a water feature. It didn’t take much convincing for me to dive in. A pond requires maintenance and is a hazard for small children and would attract raccoons from the nearby park. I settled on a pondless stream and waterfall. I researched it online and bought a kit similar to this https://www.aquascapeinc.com/products/large-pondl...

The idea of a pondless stream is that there is a sump or reservoir at the lower end that holds the water when the stream is not running. When the stream is “turned on”, a large pump at the bottom of the sump pushes water up a large hidden tube to the “diffuser” which spreads out the water to form the initial waterfall. The water then runs down the stream which is lined with waterproof “rubber” material. River rocks and pea gravel cover the rubber to disguise it and to prevent sun damage. At the bottom, a plastic grid covers the sump and the water flows over more river rocks back down into the sump.

It’s a simple design, but fitting it all into the backyard, and coming up with a pleasing design takes some doing. This Instructable illustrates some of the work that went into building it.

Step 1: ​Retaining Wall

The original solid concrete wall was tilting and looked bad. Chopping it out and pouring a new wall was not in the budget. The wall was still functional and if the tilt was increasing, it was slow enough that I wasn’t worried about it. So I decided to build a new wall in front of it. The wall was concrete blocks with rebar and concrete poured in. Strong but ugly.

I put a PVC water line and electrical cable between the old and new walls. The water line is to top up the water level in the reservoir and the electrical is to run the pump and the lights. The lights are submersible and came with the kit. I have seldom used them since most use of the stream is during the day.

Step 2: The Sump

For a stream the size I wanted the sump would need to hold about 200 gallons. This would require a hole of about 2 cubic yards. There was really only one place to put it in my yard, so we dug it. Under the few inches of top soil, my California soil is clay. I’ve seen instructional videos of petite women digging holes for trees etc. and I have to laugh. Not in my back yard. This clay is the worst. Standing on a shovel makes only slightest scratch. So I rented an electric hammer with clay spade, tried it myself, then hired a strong chap to do the work. He chopped out the clay, and I re-distributed what he tossed out of the hole to re-form my terraces.

When the hole was completed you put in the protective fabric, then the rubber liner, then the plastic grid boxes that support rocks on the top, the pump and its housing, and the plumbing.

The plumbing consists of a PVC city water feed controlled by a float valve. When the stream is running, the sump level drops, and if it drops too far, the float valve allows more water into the system. This is needed because there is always some water loss when the stream is running.

Step 3: ​Terraces

I tore down the failing brick terrace walls and using most of the same locations, replaced them with what they call “head sized moss rocks”. The rocks were delivered in large baskets. It turns out they were heavy. Who knew?

I had some day laborers help me with moving and placing the rocks. I wanted to replicate wonderful rock walls one sees in Peruvian ruins where the rocks interlock perfectly. We didn’t quite achieve that, but the rocks did stack well enough to retain the terraces. We basically put the rocks in place of the failing brick walls, keeping most of the same topography except where the stream was to go.

Step 4: Pathway

I tried chopping out the straight brick steps, but they wouldn’t budge. It was going to take way too much work to get them out. So I ended up covering them with dirt to make a smooth grade and erase the steps. In some places it would be too shallow for plants, but a lot of it would be 8 to 12 inches deep with soil.

My design called for a pathway to have a gentle curve and cross the stream. We also concluded that the path should have a destination. So I designed and built a small deck with benches. The new pathway would be a series of steps, retained by 4x6 pressure treated boards held in place with rebar pounded in vertically. I filled the steps with crushed “gold” rock.

Step 5: The Stream

I wanted the stream to curve so it wouldn’t be a straight shot downhill. The steam also had to be integrated with the terraces, basically to cut through them. I laid out string and other visual aids and finally settled on a shape that would get from top to bottom in a pleasing way.

To protect the rubber membrane from rocks etc, one places thick cloth down first (comes with the kit). Then the rubber membrane forms the base of the stream. This is not as easy as it sounds, trying to curve something that wants to lay flat, and ensuring there is enough lip (berm) on either side to keep the water contained on its way downhill.

Step 6: ​Plants

Only of few of the original plants were salvaged. My wife and I went to Home Depot and did a study of the plant labels which said how large the plants would grow. The idea was to put the larger ones on the upper terraces. At first of course they all started small. After some years though, the plants all had their own ideas about size. It still looks good though.