Build a Backyard Waterfall and Stream: Plans and Instructions (page 2 of 3)

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Planning and Tips

Planning elements to consider:

Foundation. If your soil is easy to dig, then excavate the entire project. If digging is difficult, build your stream above ground with stones for the base.

Slope. Very little slope is needed (minimum 2 in. drop per 10 ft. of stream). For faster-moving water or taller waterfalls, make the grade steeper (which also adds more sound).

Size. Plan your stream size first to determine how much water the lower basin and upper pool must hold when the pump is off. Figure 5 gallons per linear foot of flowing stream (2-1/2 ft. wide x 3 in. deep). Our lower basin (40 gallons) and upper pool (240 gallons) easily held our 75-gallon stream capacity.

Sound. For a babbling brook sound, use a waterfall height of 2 to 4 in. To drown out street noise, use 10-in. and greater waterfall drops. More waterfalls equals more noise.

Location. Waterfalls should be visible from your favorite deck, patio or inside-the-home chair. Consider a location near the bedroom if you like the sound of running water at night; you can always turn it off if it’s too loud or distracting. Make sure your pump location (lower basin) is close to an electrical source, and that you can reach the stream with a garden hose to add water as needed.

For our site, we wrapped an S-shaped stream next to a ground-level deck built into an existing perennial garden. We varied the height of the four waterfalls and the width of the stream to give it a more natural look and sound. Plus we added a ball valve to the return water line so we could speed or slow the flow rate, and control the sound level.

CAUTION: Although these pools are shallow, they can be a drowning hazard for small children. Check with your local building department for local regulations. And be watchful of toddlers.

Order Stone
When you start your stone search, look under “Rock,”“Quarries”or “Sand & Gravel” in the Yellow Pages. Call to check prices and types of stone available. Go visit dealers to get exactly what you want, plus you can select specific colorful accent boulders and flat stones for the waterfalls—then have it all delivered (for a $100 to $200 fee). Some quarries will even bag the stone by type and size (for a fee), and these palleted bags take up less space on a driveway, as opposed to piles of gravel and boulders.

For gravel (3/4-in. to 2-in. stones), figure you’ll need 1/2 ton per 10 ft. of stream, plus we used 1 to 1-1/2 tons for the upper pool and lower basin. For basic field boulders (6 in. to 24 in.) to line the stream banks, figure 3/4 ton per 10 ft. of stream. Add 1-1/2 to 2 tons more of larger 12-in. to 24-in. boulders for the upper pool and lower basin.Because we built the top half of the stream above ground, we used 3-1/2 tons of extra boulders.

If you want specialty colorful accent boulders, expect to pay premium prices—about $200 to $300 per ton. The flat waterfall stones cost about $3 per sq. ft. Avoid limestone, as it can encourage algae growth.

Map the Stream and Start Digging
After all the stone and gravel arrive, map out your design and mark it with spray paint.

We built the upper half of the stream and two waterfalls above the ground, then carved the lower half of this 15-ft. stream out of the soil (Figure A). Pick whichever technique works with your soil and go with it. Either way, keep the ibuprofen handy to soothe those sore lifting and digging muscles!

Next, dig the lower basin for the sump basin and surrounding stone and gravel. Dig a square hole at least 2 ft. wider than the basin diameter and 6 in. deeper than the height. It should be at least a foot wider than the stream.

CAUTION:
A few days before you plan to dig for your stream, call (888) 258-0808 to have underground utilities in the area located and marked.

Simultaneously, build a ring of stone for the upper pool foundation and the stream banks. Place 12-in. tall stones flat side up (if possible) so the next layer of stone will fit more securely on top (Figure B). Use a rubber mallet to pack dirt and gravel tightly around the stones to hold them in place.