There are methods to filter the water if you plan to use it. Dear EE, I live in the southeast of the country and we have had a very cold winter here. Do you have any suggestions on how to protect our plants outside in our landscaping. Your question is tough for me to answer, in that, I could use more information. Plant variety obviously has an impact on my answers.
Annuals are much more vulnerable to the cold than most perennials.
Aside from covering them or using some type of artificial heat there is not much you can do. The cold will take it's share and you will have to replace what doesn't survive. As for the perennials, I would try and cover those that would be very difficult to replace and you could supply heat, but this can get expensive. Keep in mind that some varieties will hold up to very cold weather and this should impact your decisions. You can check with a local nursery and they can provide information on the tolerance level of your plants.