I don't know about DIY RO
units, but for the cost of a commercially available unit, it is way more simpler to just get a commercial unit. Now, of course, all depends what prices are in RSA. Over here, I purchased a 6 stage RO
unit for a little over 100$ CDN. Perhaps someone will chime in about DIY
units. You may want to do a search on Google with DIY
units. Keep us posted on your finds and Welcome to AA!!