Preventing Water Quality deterioration in Finished Water Storage Facilities

Abstract

Finished water storage facilities play a key role in maintaining the quality of drinking water ultimately received by consumers. Without proper design, operation, and maintenance of these facilities, stored water may easily become stagnant and subject to loss of chlorine residual, as well as bacterial regrowth, contaminant entry, and a host of other water quality problems. Given that finished water storage facilities are part of the country's problem with aging infrastructure and that distribution system water quality is increasingly becoming a focus of regulators and customers, water utilities need all the tips they can get to better maintain these facilities. This paper outlines a five‐step approach to developing an operations and maintenance program for finished water storage facilities. The five steps are: understand your facility; define the water quality problems; evaluate alternatives to address water quality issues and select the best solutions; implement good management practices and monitor effectiveness; and, develop standard operating procedures. If utility managers implement this stepwise approach, the quality of water in the distribution system will most likely improve, which will improve public health protection and regulatory compliance. To be successful, though, this approach needs support from utility management to provide the resources operations staff will need to perform the work. For utilities that do not have a tank operations and maintenance program, this paper explains the need for such a program, and it offers a practical approach to setting it up. Utilities that already have a program in place may find additional ideas in this paper to refine their program.

Analytical Solutions to Conservative and Non-Conservative Water Quality Constituents in Water Distribution System Storage Tanks

“…Water entered Compartment A at a constant flow rate, Q in (t), and an inlet concentration of C in (t). Then, it flowed into Compartment B at the same rate as before, with a new fluoride concentration, (8), formed by mixing in Compartment A. Figure 3b shows a graphical representation.…”

“…An experiment conducted by [7] showed that ammonia-oxidizing bacteria (AOB) concentrations in the surface layer (0.3 m below the surface) were 10-20 times greater than concentrations 5 m below the surface. The deterioration of water quality in Philadelphia's ground-level storage tanks was investigated by [8]. During the summer, reservoirs were discovered to have thermal, chemical, and microbiological stratification.…”

“…During the summer, reservoirs were discovered to have thermal, chemical, and microbiological stratification. A long detention time can cause the disinfectant residuals to diminish, leaving the finished water vulnerable to additional microbiological pollutants that exist in the distribution system downstream of the storage facility [8]. A loss of chlorine residuals and subsequent biological growth can theoretically result in sour flavors [9].…”

Assessing water quality of drinking water distribution system in the South Taiwan

“…Nevertheless, more and more emphasis had been placed on distribution systems and storage facilities, which play a critical role in drinking water qualities. As a matter of fact, more and more research studies (Haas et al 2002;Martel et al 2002) considered these two factors as important barriers within water supply systems, along with the traditional multiple treatment barriers. In the past decade, emphasis had been placed on distribution system related issues, and the research results showed that the material and size of pipelines, chemical characteristics of bulk water, hydraulic conditions, distance from water facilities, and configuration of networks all influence water qualities throughout the distribution systems (Baribeau et al 2001).…”

Enhanced Water Age Performance Assessment in Distribution Networks

“…Many efforts have been made to reduce water age in order to minimise water quality degradation in drinking water networks, whether by rerouting flow paths, through valve operation [13], by increasing nodal outflows at critical dead-end nodes (through the opening of a blow-off at the hydrant site) [14], or by increasing storage tanks' daily turnover rates to reduce water ageing in storage facilities [15]. In water quality optimisation studies, the objective is often to minimise water age at the consumption nodes without setting water age goals [10,11].…”