Anything 'can' be done - how do you plan to disguise the blocks? Remember you will need to line the pond - the blocks will tear the liner so you will need to put down other stuff like old carpet to protect.

To be honest sounds an odd sort of idea to me but each to their own!

hello , this is a very simple thing to do with a little bit of thought in the building stage,I built my pond (see home page ) out of breeze block, double thickness with 1"rods every 12"running vertical, i then had it rendered by a plasterer to finish it off inside and out, because i was using a box liner all i had to do was use a proper underlay before fitting the liner, dont be tempted to use old carpet etc , the proper stuff is not that expensive and will last a lot longer, to finish the top and hide the liner i bought some scaffold planks and sanded them down, stained and sealed them perfect for the job,after 5 years i then clad the whole thing with decking boards which gave it a totally different look ,total time from start to finish 3 weeks first thing my wife and i ever built and its still going strong, good luck.

i have a 2000 gallon raised breeze block pond thats been going strong for about 12 years .i didnt actualy dig any soil out apart from footings for the blocks themselves .i built up 3 blocks high . dont use the light blocks for this as there weight helps with strength . they weigh 37 pounds each .i reinforced as ogan sais but i only had a single skin. i would have had double skin but i built seats and planters round it and it is an L shape . all these give it strength . ive put a good quality liner inside over old carpet and underlay but it must be cheep carpet as that is made of nylon so wont rot .i put a block waterfall over the l shape of the pond and use this for asthetics,filtration and oxygen . also the weight of this gives it strenght.i left the bare blocks on the inside but made sure i scraped any highpoints or sharp bits of.realy carpet etc is only realy needed if you want to move heavy plants in the bottom or have to stand in there.i renderd the outside and painted it and also built a pagoda over it to cut out light.the main thing with a square shape pond is keep the water moving in winter because if the water freezes it can crack your pond. you could do sloping edges and just render it . you can buy cement plasticiser excuse my spelling in ridgeons or b and q for about a fiver which will water proof cement which is far cheaper than what garden centres charge for waterproofing .you can get cement stains of of ebay or from a builders and also get thompsan cement seal just to make sure.i hid the edges of the blocks with very wide bamboo split down the middle .i also designed a pond and helped make it for a friend of mine . if you click on the links below you will see them or look back at some of my blogs .

http://www.youtube.com/watch?v=w-qa2oVe8g0

http://www.youtube.com/watch?v=HDzkm06Ar0s

http://www.youtube.com/watch?v=wP_EgMRPrh8

you may need to paste these links in a search bar.i hope it helps answer your question take care bye for now .