If you are wondering how much does an average Koi fish pond cost I will try to give you a rough estimate of what to expect when you start your pond. I will give you a scenario, and from there you can estimate your cost also.
The first thing we must do is layout our pond. I have decided to make my pond 15' long by 10' wide, and I will make one end 4' deep. We will take a spade shovel and dig out a rough outline the size of our pond. I used a formula for figuring the size of the liner we will use and it comes out to be 20' x 25' liner which will cost us about $320. You may think that this is a lot of money for a piece of rubber, but you do not want to go cheaper here. I recommend the Firestone EPDM liner because it is rated as puncture resistant, rated for fish, and carries a 20 year warranty.
To save money we will dig our pond ourselves. When we dig our pond we need to make a fish shelve where we will be able to add plants which will sustain any smaller fish. At this point I add sand to level out the bottom, some people buy an additional underlayment, but only if your soil contains sharp rocks. As we carefully place our liner over the freshly dug hole we will need to add water to hold down the liner. You will actually be standing in your pond while positioning your liner, remembering the one foot overhang.
Next you will purchase your landscape stones. I will use a flat type stone that allows me to place them on top of the overhanging liner which will hold it in place. The approximate cost of the stones is around $500 for small truck load. So far we have spent a little over $800 for our project.
Ok, now it is time to install our filtration system, which includes our pump, filter box, and associated plumbing fittings with our flexible hose. Total cost for my filtration equipment cost me about $700 more and after many years of trial and error I learned what system to use for clear water all the time. Now our total is around $1500 and we need to have electrical installed for our pump. This cost will vary, depending on how far are installation is from our electrical panel.
Ok we let our water filtrate for a few days so that our water temperature stabilizes. Next we will purchase our fish and plants. Koi fish can cost anywhere from $15 to $50 for a seven-inch fish depending on the type. We will purchase five fish costing us around $150, and an additional $50 for plants.
How much does an average Koi fish pond cost? Now you have an idea that you will spend anywhere from $1500 to $2000 depending how much you can do for yourself. Of course if you hire most of the work it will cost you considerably more.