Over the past 10-15 years there has been a world-wide increase in the number and size of water treatment plants utilising reverse osmosis (RO) membrane technology for the production of potable water [1]. As membrane plants continue to increase both in size and quantity, so will the potential impact of RO concentrate disposal on the environment. The issue of concentrate disposal must be addressed as an integral part of the design and evaluation of any membrane process and the method of disposal will ultimately be site specific. The costs of disposal and any treatment can have a considerable impact on the overall economic viability of a membrane plant. This paper will discuss the issues pertinent to RO concentrate disposal in the UK along with an emphasis on factors contributing to the chemical characteristics of RO concentrate.