Danny wrote:

Ive been reading up quite a lot about building fish ponds & water gardens
& what I see is that they all advocate the use of PVC liners for lining

Really? Is anybody still recommending PVC? PVC hasn't been the liner of
choice for more than a decade. HDPE or EPDM (EPDM is more flexible, HDPE
is much lighter).

the pond. Nobody talked about using bricks & cement or mortar. I'm
actually planning to build a fish pond measuring about 18'x20' in my
garden and I plan to build a more permanent structure by using bricks &
cement and subsequently after plastering, applying it with waterproof
coating. Besides the cost aspect and probably the acidity problem which
could quite easily be cure or neutralized, what are the other
disadvantages or adverse effects

Cost & pH problems are the big ones. It's also permanent. It's so much
easier to redesign a liner pond. I would think concrete would be easier,
cheaper, and no less permanent. There's many web sites discussing how to
build a concrete pond.
--
derek