Pond Design


Think of a backyard pond as one of these three types; A koi pond, water garden, or goldfish pond. Consider the key points of each during your initial research and this will set the direction for the design.

Koi Ponds

  • The primary focus is on the fish, specifically koi.
  • They are generally larger ( 50 sq. ft + ), and deeper ( 2 ft. + ).
  • They require moving (recirculating) water and filtration (primarily biological).
  • They need partial to full shade.
  • Generally they have little to no plant life.

    Water Gardens

  • The primary focus is on the plants.
  • They range in size from small containers to large earthen ponds or lakes.
  • They are generally 14" to 24" in maximum depth.
  • Recirculating water is not necessary in most climates.
  • They do best in full to part sun.
  • Typically they have few if any fish.

    Goldfish Ponds

  • This is the most popular, mainstream type of backyard pond.
  • They are stocked for even focus on the plants and fish (primarily Goldfish varieties).
  • The best depth range is 18" to 36" maximum.
  • Some water movement is desirable , though filtration may be optional.
  • Located in full to part sun.
  • Stocked with specific ratios of plants, scavengers and fish to achieve ecological balance.


    Rule # 1...put it where you (the homeowner) will enjoy it the most.
    Follow these guidelines to assure this:

  • Consider sunlight; Full sun is best except for Koi Ponds. Since most ornamental aquatic plants are sun-loving they can be used to shade the water and the fish.
  • Consider large trees; They all drop their leaves, twigs, seed pods, etc. at least seasonally, adding to maintenance. They block valuable light from pond plants. Underground roots will hamper excavation, and/or risk damage to the liner. Utilize buildings, arbors, gazebos, etc. to create any desired shade.
  • Consider topography and drainage; Level sites are generally best, though a natural slope is needed for a natural looking waterfall. It is important to keep excess surface runoff away from the pond. Achieve this by determining the total watershed (or the entire area that drains toward the pond). Small areas can be corrected by creating berms to direct the runoff. Larger areas may require a buried drainage system. Ponds will not need any consideration for overflow as long as the surrounding area drains. No matter what: always avoid low, poorly drained areas.
  • Consider access for pleasure and maintenance; Use plantings around the pond that are low and friendly (no thorns). Create or use existing walkways, paths, etc. to lead and welcome visitors. Create or use existing decks, patios, gazebos as relaxing sites for viewing. A bench or even a large rock might suffice for this purpose. Creating access to the water's edge allows the best view and optimum fish feeding spot. Any in-pond maintenance will be easier as well. Construction of footers may be required for support of foot traffic near the edge. Remember that any out of pond equipment such as pumps, filters, etc. will require access as well.
  • Consider water and electricity; The garden hose will be needed for filling, occasional top-offs and cleanings. Electricity is not required for simple Water Gardens, though it is a must for fish ponds of any kind. Some pond items that require power include Pumps, U.V. Clarifiers, Decorative Lights, Pond Vacuums, and De-icers. Any needed electrical lines should be professionally installed and extension cords (buried or not) should only be used temporarily.
  • Consider proximity to the house; Generally closer is better as views from inside are nice, allowing the pond to become a day to day part of the occupants lives. Seasonal aestetics should be considered though, as well as elevated humidity levels.


  • Generally the pond should be as large as the owners space and budget (time) allows. Most current pond owners will express desire for a larger pond if asked. the larger the pond the more stable the enviroment will be in terms of water temperature and chemistry, making excessive algae growth less likely.
  • Based on these factors the minimum size for consideration of a Water Garden or Goldfish Pond should be 50 sq. ft. (surface); and 100 sq. ft. for a Koi Pond.
  • Smaller ponds or even containers are fine when stocked properly and make a great "introduction" into a larger pond. Smaller ponds should be closer to the house to avoid "getting lost" in the landscape.
  • Determine the appropriate flexible liner size by first determining the maximum length, width and depth of the proposed pond. Figure the maximum length and width by placing the shape into a square or rectangle then measure. (See more on depth below). If the maximum depth is 18" then add 4 feet to the length and width measurements. Any/each depth increase of 6" an extra 1 foot must be added to the length and width. Therefore a 24" depth will require 5 feet added to the length and width;...30" add 6 ft....and so on. These measurements allow a minimum of a 6" overlap beyond the upper edge. More overlap may be needed for certain finished edges, so figure accordingly. Shelves or step down depth changes do not warrant consideration for figuring liner size, only the very maximum depth measurement.


  • The rule here is "keep it simple". Think in terms of the actual angle of view as oppossed to the way the shape appears on the design drawing. The shape is not as important as the amount of visible water surface. The overall theme of the surrounding garden (assuming one exsists), will dictate the need for an informal (natural) shape or a formal one such as a rectangle or circle. Since liners are cut in square/ rectangular pieces, choose shapes that fill a square or rectangle as fully as possible to avoid excess waste.
  • Consider water circulation and filtration especially in fish ponds. This is aother reason to create a more "open" shape, avoiding "bays" or "coves" that may become "dead spots" void of water movement and filtration.
  • Shapes to avoid when using a flexible liner include "L" and "T" shapes or any shape with a sharp inward angle. This creates a large fold causing a pocket of still water unless the fold is taped down.


  • This will be greatly based on the type of pond as originally determined.
  • Water Gardens - 14" to 24" max. depth, waterlilies grow best at 18" to 24".
  • Goldfish Ponds - 18" to 24" max. depth, overwinters hardy plants/fish to Zone 5.
  • Koi Ponds - 24" to 60" max. depth, majority should be 18" to allow good view of fish.
  • Use of a simple electric de-icer is reccomended in Zone 6 and lower to prevent the need for extra depth to assure winter survival of hardy plants and fish.
  • Consider creating "shelves" or shallow water areas. They provide enviroment for shallow water (bog) plants, fish viewing areas,quickly warming water in the spring,and wildlife access. Consequently they provide access to unwanted wildlife or predators and may contribute to algae growth. If shelves are used, then make them only as large as needed. The deeper floor space will be more valuable.
  • Specify a near flat bottom. The sides (walls) should have a slight inward (from top to bottom) pitch of 5 to 10 degrees. This is roughly 1" inward for every 12" of depth. This will provide maximum floor space for plants, pumps, etc.; makes maintenence easier, deters predators, creates less liner waste, deters algae, and provides shade for fish. "Bowl-shaped" should be avoided.
  • Remember that when using pre-formed, rigid liners the size, shape and depth are pre-determined and cannot be altared.



  • Pros: Tough, durable, flexibility in design.

  • Cons:
    - Most expensive and labor intensive material option.
    - Difficult to install, Particularly for the in experienced.
    - Susceptible to freeze damage/cracking and difficult to repair.
    - Concrete ponds require a sealing finish or paint and other materials such as rebar.
    - Water quality and Ph will have to be monitored for a period after set-up.

    Flexible Liners - Flexible rubber (EPDM) is sold/used nearly exclusively now in the U.S.; PVC may still be available. Always specify fish grade or "fish-safe".

  • Pros: - Least expensive material per sq. ft. for pond construction.
    - Provides flexibility in design regarding size, shape, and depth.
    - Provides more options and flexibilty in edging or finishing the pond.
    - Available in standard pre-cut or custom cut to nearly any size application.
    - Relatively easy to install and repair when needed.
    - Durable; last up to 20-30+ years and not susceptible to freeze damage.
    - Proven; most widely used material for the last 25 years.

  • Cons: - Susceptible to U.V. (sunlight) damage, specifically improperly installed and PVC liners.
    - Not as tough as other materials.
    - Folds cannot be avoided and large ones may require taping down.
    - Underlayment material, though possibly not necessary is highly reccomended.
    - Supportive forms are required for unstable soil or above ground installations.

    Pre-formed Liners - Rigid fiberglass or plastic shells.

  • Pros: - Easiest material to install.
    - No guesswork figuring size, shape or depth.
    - Tough, durable; high quality fiberglass can last 50 + years.
    - Not susceptible to freeze damage.

  • Cons: - No flexibility in design.
    - Higher cost than flexible liner, up to 5 times as much per sq. ft.
    - Limited shape, depth choices.



  • Research ideas/options thoroughly. The choices are nearly endless. Informal pond edging is almost always natural rock and plantings, best used in combinations. Avoid specifying an entire rock perimeter as this will not achieve a truly natural look. Plantings must be used to "soften" the look and break-up the otherwise "cold-looking" rock edge. Formal pond edges are best suited for materials such as brick, wood or cut flagstone.
  • Supportive footers should be built under the edge of a flexible liner if there will be heavy foot traffic , such as the edge of patio or walkway. These footers may be poured concrete or block and set prior to excavating the pond. Footers may also be created by stacking natural wallstone "inside" the pond on a shallow shelf created for this purpose.
  • Remember this is the transition point that takes the eye from water to surrounding land-scape and vice versa. Try to incorporate existing looks, themes, colors, etc., where-ever possible. A bog garden edge certainly will look most natural. Definitly learn and understand, or be certain the homeowner understand pond predators when determining the proper edging.

    Waterfalls and Streams

  • Take time to study natural ones. Note the variance in rock sizes and placements.
  • Specify construction to be a vertical, or a series of vertical drops as opposed to a more horizontal run. This will create more visual and audible impact and is less likely to promote mossy algae growth on wet rocks.
  • Design waterfalls only where a natural slope exists. Any type of infomal waterfall built on a level spot will most certainly appear contrived if not downright silly.
  • Waterfalls/streams are prone to leaking due to escaping water, so be certain to specify thorough waterproofing by completely underlining with a flexible liner (preferably an extension of the pond liner) set to direct any escaping water back to the pond.
  • Natural rock looks best, though it can be expensive. Use varied sizes leaning toward larger ones to create more visual impact. Utilize Black Foam Sealent to direct flowing water "over" rocks, and to create pools.
  • Pre-formed waterfall/stream units are available and some are very realistic appearing, though addition of some natural rock is typically needed to create a truly "natural look".
  • Waterfall "tanks" or "boxes" have become very popular. They work ideally to create the appearence of a "sheet" of cascading water. They enhance filtration and require rock for disguising. Always specify waterproof underlining even when pre-formed pieces or waterfall tanks are used.


    Mechanical Filtration focuses on water clarity.
  • Relatively inexpensive; most operate in-pond (submerged); require minimum weekly attention, and cleaning can be cumbersome.

    Biological Filtration focuses on water quality and clarity.
  • Wide range of options and prices; requires less attention (bi-monthly); operate out-of-pond and must be disguised; available in pressurized (bead) or gravity-return styles.

    Ultraviolet (light) Clarification/Sterilization assures water clarity.
  • Requires almost no attention when operating; available for in, or out of pond use; lamps (bulbs) require changing every 10-12 months- $30 to $70 retail.

    Combination Filters are extremely popular and practical.
  • Most utilize all three types of filtration; each type will benifit and enhance the other.
  • They operate out-of -pond, though the fact they are pressurized and compact in size allows ease of disguise in the landscape. They can even be partially buried.

    Suggested further reading:
    Ortho's All About Building Waterfalls, Ponds, and Streams
    Meridith Publishing 2006

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