Welcome suze!
Yes, but why? Is your tap water temperature super cold and you are asking if you should add warm water to make it relatively the same temp as your pond water? Sure you can do that but just curious, why are you doing water changes to your pond? Is it a small indoor pond? Be sure to use water conditioner. Again, welcome!
How much water are you talking about and why do you think it needs to stay heated? Just allow the temperature to become equalized by the ambient air, before you add the fish. Get a water thermometer. I guess you could use buckets of warm water, but if your pond water is cold enough that you need to heat it, then it sounds like it’s too cold for you to be doing a water change.
Tell us more about your pond and the climate where you live.
How many gallons?
How many fish?
What type of fish and their size?
And why you're doing water changes? You may need to top off the water due to evaporation and scarce amount of rain. But water changes are normally not necessary unless your pond has been exposed to some sort of toxin.
I haven't changed or added water to my pond in years. I let nature take care of that when it rains. There are areas with little rain and you may need to add some, I get that.
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