Well if addressing TDS is ...

Well if addressing TDS is the main concern then there are alternative methods that can be adopted. For instance universities in the U.S. have found that Moringa extracts can reduce tds in water by 30%. The contact time that has to be given is 3 hours. The water then needs to be skimmed from the top as the sludge settles at the bottom. RO is a good solution only to address high TDS. For other factors such as turbidity, removal of heavy metals, hardness and microbial contamination there are several options from Zeolite Filters, Template Assisted Crystallization technology and a wide array of biocides. 

Water treated by RO still require a disinfectant present to eradicate microbial contamination and a biocide with residual presence in the water is the correct solution. Many RO filter suppliers provide a follow on UV treatment. UV treatment is good if the water is going to be consumed immediately, but if the water is going to be stored a biocide present in the water will provide greater safety.