Microbiological contamination water activity

Natural degradation processes that occur in days or weeks in surface waters may take decades in groundwater, where flow rates are slow and microbiological activity is low. This limits the potential for natural purification through flushing or biological consumption. Once contaminated, groundwater is difficult and expensive—in many cases impossible—to rehabilitate. 

Contaminants polluting our water may be chemical or microbiological. Chemical hazards are caused by the chemical compounds which may be inorganic or organic. They may be present in the water due to the natural source, such as arsenic, which is a natural component of some soils and may be dissolved in groundwater. Alternatively, the contaminant may have been introduced into the ecosystem or the water source by human activity, such as pesticides, that trickle down sediment layers and streams and find their way into our freshwater. Some contaminants are by-products of chemicals used during the disinfection processes applied. 

The use of purified water is recommended to keep the initial contamination low and thereby to hold the Ph. Eur. requirements for microbiological quality of non-sterile pharmaceutical preparations. The requirements of the chemical and microbiological purity of purified water are well defined, see Sect. 23.3.1. The concentration of ions in purified water is low, which is an advantage as they may catalyse degradation of active substances and excipients and form complexes with active substances and excipients. 

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