Estimating the Cost to Build a Pond
The cost to build a pond in your backyard will vary greatly depending on individual circumstances. Here I am going to provide a framework for estimating a budget for building a pond and take you through a hypothetical example to bring together the information and the calculations that I provided on the previous pages. At the bottom of the page is a customizable calculator that automates these formulas. I have pre-populated the calculator with values from the example, but they can be changed to better fit your own plans. You can also use the Pond Shop to find current prices for the products that you need and plug those into the calculator. If you are new to owning fish ponds, the information on this page will be clearer if you have read through the previous pages on this site that explain each of the steps in building and stocking a pond.
Our hypothetical example will calculate the cost to build a pond that is roughly rectangular in shape and is 20 feet long, 15 feet wide, 4 feet at its deepest point with an average depth of 2.5 feet. It has a waterfall/filter at a lateral distance of 20 ft and height of 3 ft above the top of the pump.
The cost calculation assumes that you do most of the labor yourself though you can plug in a number to pay for help with the excavation and installing utilities.
1) Calculate the pond volume
- Surface area = 16 x 10 = 160 Sq. Ft
- Volume = 160 Sq. Ft. x 2.5 = 400 Cu Ft
- 400 Cu. Ft. x 7.5 gals/per Cu Ft = 3000 Gals
- Border Area = 2 x (16+10) x 2ft wide
2) Determine the size of the liner
- Length = 16 Ft + 2 x 4 Ft + 2Ft = 26 Ft
- Width = 10 Ft + 2 x 4 Ft + 2 Ft = 20 Ft
- Surface Area = 26 Ft x 20 Ft = 520 Sq Ft
- Border Area = 2 Ft X (16 Ft+10 Ft) X 2 = 104 Sq Ft
3) Infrastructure Costs
- Plug in number dependent on how much work you do yourself and local prices
- For this case, I used $200 assuming I did most of the work myself but paid for some help
4) Cost of Lining the Pond
- Cost are calculated for liner, underlayment, river rock 1 and 1/2 inches deep and edging stone as follows:
- Square footage of liner x unit cost for 45ml EDPM liner from Amazon
- Square footage of liner x unit cost for undelayment
- Square footage of liner less square footage of border x unit cost for river rock
- Square footage of border x unit cost for edging stone
- The cost of river rock and edging stone varies greatly depending on the quality of the stone selected and the vendor. You can input your own unit cost and the calculation will be updated.
- I used middle of the road cost for this example but I usually use natural rock from my property and the excavation for edging so the actual cost can often be zero
5) Cost of the Filter System
- Turnover the pond volume once per hour and include capacity loss due to height and volume
- 3000 gals per hour at equivalent height of 5 height (lift of 3 ft and distance of 20 ft)
- Assumes the use of the Torpedo Pump and related degradation table to select model
- Torpedo Pump 4000 provides 3500 gallons per hour at 5 ft which is more than required to turn over the pond once per hour.
- Actual cost of the Torpedo Pump 4000 + filter screen is $195
- Assumes a combination waterfall/bio filter set up
- Prices varies depending on vendor and filter capability
- Assumes a mid price product and the spreadsheet considers volume requirements in selecting models
- In this case the combined cost is $600
- Hose/Pipe is the unit cost for flexible PVC x the distance from the pump to the filter box
6) Cost of Stocking Fish and Plants
- Price for the 4 – 5 inch domestic koi from That Fish Place
- Stocking guidelines and size of pond used to calculate number of fish
- Price for lilies, submerged plants and bog plants from That Fish Place
- Stocking guidelines and size of pond used to determine the numbers of each plant
- Just cells for more plug in numbers for add on items, miscellaneous costs and potential taxes and shipping. I used 15% for this number
The spreadsheet below is pre-populated with data from the hypothetical. You can change any of input fields in blue but I suggest you review the spreadsheet and understand the calculations before making any changes.
Of course there are a lot of other features that can be added once you get started with this hobby– a patio or deck for viewing, outdoor furniture to put on the deck, a fire pit, landscape lights, border plants etc. This is a good pro forma for estimating the budget for building and stocking a basic koi pond only.
Pond Cost Calculator
Now comparison shop at the Pond Shop to get current prices to calculate the cost to build a pond