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Build a Backyard Waterfall and Stream

This cascading stream flows into a gravel bed, not a pond, so it stays clean with little maintenance.

FH04JUN_WATERF_01-2Family Handyman
Create a rippling, rock-lined stream with multiple waterfalls in your backyard. Use gravel and stone filters and a heavy-duty pump to reduce maintenance and maintain water clarity.

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Time
Multi-day
Complexity
Simple
Cost
Over $500

Step 1: Overview of DIY Pondless Waterfall

Completed stream

Placing rocks

We’ve all stopped, gazed and listened upon encountering a rippling brook or small backyard waterfalls—to soak up the serenity that nature provides. But where is that spot when we need it most? Since you probably can’t drive and hike to a tranquil location after a hard day’s work, you can use this project to help you recreate these all-too-fleeting moments in your backyard. And you can build your stream in two weekends.

We designed this DIY pondless waterfall stream to eliminate the filtering and cleaning maintenance that comes with ponds, making it one of the best backyard waterfall ideas in our opinion. The trick to low maintenance is to let nature (layers of gravel and stone) filter the water, using an underground sump at the lower end to catch the filtered water before pumping it back up to the top of the stream. All you have to do is occasionally add water to replace what evaporates—and rainfall may handle this task for you. In this story, we’ll show you how to slope the stream, lay the liner and install the pump and the catch basin as well as landscape the stream. We’ll help you plan the ideal location and size of your stream, and tell you how to select liners, pumps and stone. We won’t get into pond waterfall kits that are available either online or at home centers. We chose to build our system with parts and components that are readily available and less expensive than pond waterfall kits. They’ll give you more flexibility to design the stream that best fits your yard.

You can complete this project successfully even if it’s your first water feature. But it’s heavy work. The only special tools you’ll need are a strong wheelbarrow (one with pneumatic tires is best) and a two-wheel ball cart for moving and placing heavy boulders.

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.

Step 2: Select a location

Sit in a favorite spot and visualize where a stream with waterfalls would fit into your landscape—perhaps near a patio or deck.

Waterfall features: 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 and other backyard rocks 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.

Figures A-C: Stream and Waterfalls Layout

Use these illustrations to help you plan your water feature, and learn how to build a pondless waterfall.

Step 3: Order Stone

When you start your stone search, look under “Rock,” “Quarries” or “Sand & Gravel” online. 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. 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. Avoid limestone, as it can encourage algae growth.

CAUTION!

A few days before you plan to dig for your stream, call 811 to have underground utilities in the area located and marked.

Step 4: Map the stream and start digging

Photo 1: Design the stream

Haul in your boulders and stones and place them around the worksite. Outline the location of your stream with a garden hose, then paint a line around it. Also use paint to mark waterfall locations and ideal spots for large decorative boulders.

Photo 2: Start digging

Dig the hole for the lower basin so it sits below the level of the streambed. Place boulders to build up the sides of the upper pool and upper portion of the stream, which are above the original grade (Figure A). Pack dirt and gravel to hold all stones in place.

After all the stone and gravel arrive, map out your design and mark it with spray paint (Photo 1).

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.

Simultaneously, build a ring of stone for the upper pool foundation and the stream banks (Photo 2). 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.

Step 5: Complete the lower basin first

Photo 3: Prepare the basin and pump

Drill holes in the basin using three different size hole saw bits (see Figure C). Prime, cement and attach the hose adapter to the pump.

Photo 4: Line the basin

Lay the fabric underlayment and rubber liner in the basin hole, then add the pump basin with pump. Attach the hose. Then add stone layers (Figure C) and the basin lid.

Use a 2-in. hole saw bit and drill holes every 4 in. in the bottom third of the pump basin (Figure C and Photo 3). Repeat the process with a 1-in. hole saw bit for the middle third, then use a 3/8-in. bit for the top third.

Remove sharp objects from the bottom of the basin, then lay in the underlayment and liner. Calculate the size carefully and cut the underlayment first. Then cut and fit the liner so it is tucked in all corners and extends about 2 ft. out of the hole in all directions. With the pump basin in place, insert the pump, connect the water line and lay it in place to ensure it will reach the top of the upper pool. Add layers of stone around the basin and top with the lid (Figure C and Photo 4).

Step 6: Dig out (or build) a long staircase

Photo 5: Dig the streambed

Carve a winding stream bed 6 to 8 in. deep, 2 to 3-1/2 ft. wide. Dig the channel so it stair-steps down at waterfall No. 3, and dig 3- to 4-in. deep pools below waterfalls No. 2 and 3 (Figure A).

Photo 6: Build up the waterfalls

Pack dirt and gravel around the border stones to build waterfalls No. 1 and 2 above the existing grade. Level the rows. Inspect the entire streambed and remove anything sharp. Tamp down the entire stream, banks and upper pool area.

First, at each waterfall location, dig down to the approximate depth of the drop you desire or build up the fall if you’re working above grade. This gives you a streambed depth target. Now move to the bottom of the stream and carve a 2 to 3-1/2 ft. wide streambed 6 to 8 in. deep, sloping upward as you dig upstream to meet that streambed depth target at each waterfall (Photo 5). Then dig out shallow pools below waterfalls as needed (Figure A) to slow the water flow.

Since we built above ground for the upper section of the stream, we next added a level row of stones for waterfalls No. 1 and 2 (Photo 6). Pick the height you desire. Use 6- in. tall stones to frame the banks. Also finish compacting a gravel and dirt mixture to the inside and outside of the upper pool stones. Then tamp down the upper pool area and the streambed.

Step 7: Lay the liner and position waterfall stones

Photo 7: Spread the liner in the streambed

Lay the underlayment and a rubber liner into the streambed. Leave 3 to 4 in. of slack in the liner at the base of the waterfalls, extend about 2 ft. up each bank and overlap the basin liner by 2 ft. Place decorative boulders at waterfall locations.

Photo 8: Line the upper pool

Lay the underlayment and liner over the upper pool, overlapping the built-up boulder edges. Overlap the lower liner by about 2 ft. Backfill stream edging boulders for stability.

Position the fabric underlayment and liner to extend from the lower basin to the upper pool, with slack at the base of each waterfall, because placing boulders can stretch and rip a tight liner (Photo 7). Place decorative boulders at the side of each waterfall, and add an extra piece of rubber liner underneath each heavy stone to protect the base liner. For stable, above-ground stream edges, backfill the edging stones with a gravel and dirt mixture and compact it (Photo 8). Next, lay the final piece of underlayment and liner in the upper pool so it tucks in at all corners and extends 2 ft. out in all directions. There’s no need to tape the liners to each other; just make sure the top liner overlaps the liner underneath it by 1-1/2 to 2 ft. Then add the top layer of stones around the upper pool.

Step 8: Add spill stones and foam the gaps

Photo 9: Build up the waterfalls

Set decorative boulders at each side of waterfalls No. 1 and 2. Then coat the bottom of the flat spill stones with foam sealant so they adhere to the liner. Wedge stones into cracks between the spill stones and the sides of the stream bank.

Photo 10: Fill gaps with foam

Force gravel along all sides and under spill stones, then apply foam sealant in the gaps so water flows only over the top of all spill stones.

Once you place the decorative boulders at the waterfall locations, place all the flat spill stones. Apply black expanding foam sealant, designed for ponds and waterfalls, to the underside to adhere them to the rubber liner. Now fill all gaps with stones to force water to go only over the waterfall (Photo 9). Then apply foam sealant to all sides and to the underneath of each spill stone to create a good seal (Photo 10). After the foam has dried for 30 minutes, take your garden hose and run water down the stream. Look for any water trails (leaks) along the spill stone edges and underneath. Fill any leaks with more foam and repeat until all water goes over the top of the spill stones.

Step 9: Add gravel and clean the stream

Photo 11: Add boulders to complete

Add a top layer of small boulders to complete the upper pool and streambed. Place steppingstones in the middle of the stream and the stones below the waterfalls. Cover the rest of the streambed liner with gravel.

Photo 12: Clean the rocks and trim the liner

Fill the bottom basin with water and plug in the pump. Spray down all stones and the stream until the water from the pump runs clear. Place the hose from the pump into the upper pool. Trim off remaining exposed liner and adjust stream flow by moving rocks and adjusting the ball valve.

The final construction step is to place steppingstones in the middle of the stream to make it inviting for people, birds and pets. Then carefully layer in gravel to cover any exposed liner (Photo 11).

Spray down the entire stream area with a garden hose nozzle until the water level rises above the gravel in the bottom basin. Now power up the pump and direct the pump hose away from the stream. Keep washing down the stream and rock until the water from the pump hose runs clear. Then insert the pump hose into the upper pool (make sure it is hidden), and finish your stream by trimming and covering any rubber liner that shows (Photo 12).

Now it’s time to take that favorite seat, with a cold beverage in hand, and relax to the soothing sounds of your new stream.

Pump Sizing

Submersible pumps are rated by gph (gallons per hour) at a specific discharge height (known as head or lift). To calculate the gph you need, figure 150 gph for each inch of your widest waterfall. Next, to figure the head/lift you need, calculate the distance your water line travels from the pump to the upper pool (measure vertical and horizontal; 10 ft. of horizontal distance = 1 ft. of vertical rise). Look for a high quality pump (bronze, brass or stainless steel; not a cheap sump pump) that can exceed the gph and lift you need.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Level
  • Rubber mallet
  • Spade
  • Utility knife
  • Wheelbarrow
Hand tamper, scissors, ball cart (for moving boulders)

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Ball valve and clamps
  • Decorative boulders
  • EPDM pond liner
  • Field boulders
  • Gravel
  • Hose kit and connections
  • Large waterfall pump
  • PVC primer and cement
  • Sewage basin (18” x 30”) and lid
  • Two hole saw bits (2” and 1”)
  • Underlayment fabric
  • Waterfall foam sealant

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