The SC and TES rates have remained at the same level since their introduction in 1995. During the period, many new sewerage infrastructures including the Stonecutters Island Sewage Treatment Works with Chemically Enhanced Primary Treatment Process, were completed to provide better sewage services. Consequently, the operation and maintenance cost of sewage services has increased substantially. Adjustment of sewage services charges will further enforce the Polluter Pays Principle and encourage the public to conserve the valuable water.

The legislature had approved the gradual increase of the SC within ten years starting from 2008. From 1 April 2008, the SC rate has been revised from the original $1.20 to $1.31 per cubic metre of water supplied. The rate will then be gradually increased by 9.3% per annum until $2.92 per cubic metre of water supplied on 1 April 2017 and onwards. 

Also, the Government has competed the trade effluent survey for the TES chargeable trades in end 2007. The generic COD values of the effluent from these trades were reviewed. According to the survey result and the cost recovery principle, the respective TES rates were adjusted.  The proposal was approved by the Legislative Council and took effect from 1 August 2008. The operators of three trades, namely "Bleaching and dyeing of garments", "Textile stencilling and printing" and "Laundries" are no longer required to pay TES as the pollution level of their effluent is comparable to that of domestic sewage.