Waterproofing a fountain basin

I have a basin constructed of cement block 24 inches square and 14 inches deep There has been an epdm liner in it but it has recently chosen to leak. I am in the midst of removing the drilled basalt column and poured in place concrete base. My question is of the most cost effective material to resurface/waterproof the interior. My thoughts run from Sani-tred to paint on stuff to tile, but never having done anything in this area I am at a loss. I would really appreciate some insight from experienced pond/fountain folks.