Prepare a separate tub or tank for your koi to rest. Although it depends on the size of koi, a 100-300 gallon tank will do. You can use blue show tanks as well.
Fill the tank with fresh dechlorinated water, well water, or better yet water from your exiting pond, providing your existing pond stock is in good condition.
Filtration system for the tank is ideal. If you do not have a filtration system, provide sound aeration with an air pump.
Keep the water temperature at 72 F or more. If the tank was small enough, one or two aquarium heaters will do the job.
Please add salt to make 0.3% concentration. (3 lb salt per 100 gallon water)
Read all the details of koi care after receiving in your home.