Large concrete pool renovation

Hello,

We bought recently a house in Brazil and skilled labour and good materials are very hard to come by here.

I'm looking for someone to point me to some basic instructions on how to make a very large old concrete pool water proof with general materials (not branded stuff, because it doesn't exists in Brazil)

I have had pool builders there who talked about putting tar as the as coat over the reinforced concrete but that sounds like a very ancient method to me. We had various people suggest glass fibre coats but the materials here are of really questionable quality.

Ideally we put several layers of the reinforced concrete structure that's already in place and finish it off with some nice tiles.

Thanks!