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/Aquatic Gardens, Design, Construction & Maintenance

Plumbing Water Features

By Bob Fenner

Large systems can make use of butterfly valves for on/off

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner

Plumbing your water effect can be the easiest or worst part of construction and maintenance. This article attempts to help you avoid the two most common plumbing pitfalls: under-planning and poor construction.


First of all, in any design, consideration should be given utmost to the desired result/s. That is, what will the final effect be? Quantity and quality of sights, sounds and utility can be achieved only with adequate planning. Plumbing is frequently a sore area in this regard.

In designing your water effect give thought to the following plumbing lines: 1) Intake(s) 2) Discharge(s) 3) Filter and Pump 4) Drain(s) 5) Overflow 6) Fill line. Before discussing these we'll discuss some beliefs, facts, attitudes and methods regarding plumbing in general.


Thank goodness this is the nineties! Hurrah for plastic pipe! Most of the plumbing you will do on your water effect may be done with PVC (poly-vinyl-chloride) pipe. I suggest schedule 40 (rated 400 pounds per square inch) for adequate strength/thickness. Hot on the scene is the use of flexible pvc pipe that may be joined to rigid with a special solvent. Pipe and fittings are readily available and easy to use. Cutting tools are available for lower and lower cost or rental other than the standby hacksaw or friction-string trick. Ask your dealer about solvents that are appropriate for use. There are many that require no primer and work well under less than ideal conditions of dirt and moisture.

Pipe Sizing:

Commonly pipelines are undersized, rarely oversized. Rules of thumb: Never size down an intake or discharge line. The size of the fitting at the volute (outer casing of the pump) should not be made smaller. Among other ills this will reduce flow and motor life and increase energy costs; in other words, don't do it! Overflow and drain lines should be way oversized. Anything smaller than 1 1/2" is a bad joke; especially if there is a long run with any number of turns.


By and large these should be 1) Schedule 40, (sometimes 80) 2) Plastic (to avoid corrosion, poisoning) 3) Ball type (best flow, shut off design) 4) Union, true union (flush) if possible (so you won't have to cut the piping for service, repair).

At right: three out of four here... what happens if you have to take apart a non-union fitting? Cut and re-build. The second image: now, that's better. 

These will give long, dependable service with less induced drag (friction) than gate valves of any sort. Systems using plumbing greater than four inch should consider butterfly valves. Ball, flap and spring-type check valves should also be plastic.

Check- or one-way valves are of such considerable importance you should thoroughly investigate them before actually digging.

Unions are special thread-to-thread fittings that allow easier repair and replacement of plumbing without having to cut lines. Where possibly cost effective, use true-unions, especially at valves and pump connections.


It goes without saying that the best layout is the least complicated and conspicuous. If possible, plumbing that's not outside the water holding basin(s) should be within the basins. This is especially possible in concreted basins, particularly ones using a liner as a water-impermeable membrane (drawing, photo). Their plumbing may be lain down over the membrane or attached to the wire reinforcing mesh and covered by concrete. These lines may enter and exit the basin above the water line. If the plumbing is to be fitted through the basin below water level, care will have to be taken to prevent leaking. Internal  liner trenching at right.

Plumbing should be buried at sufficient depth to prevent breakage or rupture from freezing; check local codes for guidelines.

1) Intakes:

Intake lines should be as many in number and large of size as practical. For biological ponds, the intakes should be situated somewhat off the bottom. So-called bad water should be left below where it may be vented to waste via the drain line.

2) Pump_and_Filter_Lines:

As to the size of lines from the intake line/s, the pump may be reducer bushing fitted (bushed) to the size of the volute right at the pump. As you found in the last piece concerning pumps, most are made to push, not pull and so care should be taken in designing and building the plumbing lines to reduce restriction on the intake side as much as possible. If the pump system is above resting water level, check and/or ball valves should be installed right before and after the pump. If the pump system is below resting water level, union ball valves will allow you to clean out your trap, do pump repairs or removal without much water loss/flooding.

While providing plumbing (= cutting in) to the pump and filter, there arises a possibility of providing a vacuum-line. This specialty plumbing is appropriate in cases where there is inadequate self-cleaning by design.

A vac-line may be arranged either through a pool-designed skimmer system in the basin, or two two-way or a three-way valve system with a hook-up for periodic system vacuuming. This vac-system is something you may want to provide for initially in design and installing the plumbing.

3) Discharge:

These lines should be as short as possible. There is generally not much to be gained by sizing up the discharge(s) beyond that of the size of the pump. To some large extent much efficiency is lost through extra turns, more length of pipe. Plan and measure twice, cut and glue once. Discharges should be non-restricted at their ends. If possible, at least one of the discharge ends should be left completely open.

You may want an alternate discharge to vent water for irrigation, drainage or to dump the system.

4) Drains:

You will thank me and yourself later for installing a drain line or at least a definitely deeper area, possibly with a sump. A drain and/or sump will greatly facilitate cleaning, partial water change and dumping. We have found it expedient to pre-insert a drainage box (conduit) or in very small systems a bucket with rocks to leave a depression in the deepest part of the basin. The concrete mix is placed around this area to provide a slope. If possible, use gravity to drain the feature, situating a ball valve for control in the most convenient, accessible area. Take care that this waste water goes where you want it to go; where it will do no harm.

It is often appropriate to connect the overflow line with the drain line and run them collectively to waste, saving cost and flushing water.


Talk with anyone who's built an aquascape and they'll concur; they should have incorporated an overflow in their design. There will be times when all systems will purposely or accidentally be overfilled.

All systems require one or more designated overflows.

The simplest overflow is the lowest edge of the system. You might make this area intentionally and provide it with a screen to keep debris out and livestock in. As previously stated, imagine a flood of biblical proportions when sizing your pipe; the bigger the better.

Detail showing proper PVC layout and foundation work for overflow lines. The large pipe at bottom is directly tied to the waste/sewer drain. The other, taller lines with the main drains in the pond itself. Later, these lines will be fitted with a slip coupler near their bottom and these risers can be wiggled out to drain solids and heavy water from various parts of the system. The same lines will also serve as overflow stand pipes for the system, as their tops will be cut to be at near desired water level in the main pond.

6) Fill Line:

All systems will benefit by an automatic refill or continuous-drip make-up system. You can provide one of these by tapping off a pressurized irrigation line or potable water line. There are a wide range of available types, costs for floating to electronic devices.

Definitely cut-in a shut off valve for the make up system so you may terminate the flow manually. If the make-up is automatic, I strongly suggest utilizing a very small diameter feed line, or otherwise restricted flow rate, should something go awry and the system over-fill... flooding property, possibly poisoning livestock.

For small systems (up to a few thousand gallons) I'd much rather just refill while I'm standing there with my coffee, and then shut off the new water definitely when leaving.

Here's a handy parts, tool list for a plumbing kit:

Plumbing Checklist

PVC             Copper

PVC Bucket Torch Kit

PVC cutters Torch

PVC Primer Igniter

PVC Glue Emery Cloth

711 - Grey Solder

710 - Clear Flux

335 - Flex to Rigid Tubing Cutters

297 - ABS to PVC

Teflon Tape

Other Supplies Other Tools

Teflon Paste Hacksaw

Silicone Sealant Channel-lock pliers

Rags Measuring Tape


It may seem from this discussion that you're going to have to become an engineer and plumber in order to build your water feature. Such is not the case; modern plumbing is easy with all the new tools and materials. By following the advice presented here and in this series you will be able to properly plan, construct and maintain your effect with a minimum of hassle.

Make a checklist of all the line types suggested above and draw them out in your plans and ground. You're done.

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner
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