Recycled Water Quality Standards: Sanitary Hygiene or Class 1 Water Quality Standards?

The utilization of recycled water is increasingly being implemented in office buildings, industrial areas, hospitals, and modern residential complexes. Amid concerns over clean water scarcity, water recycling systems have become an important solution for efficiency and sustainability. However, one crucial question often arises: what quality standard should be applied to recycled water? Is it sufficient to meet hygiene and sanitation standards, or must it comply with Class 1 water quality standards?

The answer to this question cannot be generalized, as it strongly depends on the intended use of the water.

What Is Recycled Water?

Recycled water is used water (greywater or wastewater) that has undergone physical, chemical, and biological treatment processes so that it can be reused. This water is generally utilized for:

• Toilet flushing
• Garden irrigation
• Cooling towers
• Certain industrial processes
• Raw water for further treatment

The quality of recycled water is controlled through key parameters such as turbidity, BOD, COD, heavy metals, and the presence of microorganisms (E. coli, total coliform).

Hygiene and Sanitation Standards

Hygiene and sanitation standards are applied to water that is not intended for consumption but may still come into indirect contact with humans. The main focus is to ensure that the water:

• Does not contain harmful pathogenic bacteria
• Is free from unpleasant odor and strong color
• Does not pose a risk of infection through skin contact or aerosols

These standards are generally sufficient for uses such as:

• Toilet flushing
• Floor cleaning
• Garden irrigation
  Building cooling systems

From a technical perspective, water meeting hygiene and sanitation standards usually only requires filtration, biological treatment, and disinfection (chlorine, UV, or ozone).

Class 1 Water Quality Standards

Class 1 water quality standards represent the highest level in water source classification. Water in this class is suitable for:

• Drinking water sources
• Protection of sensitive ecosystems
• Pharmaceutical and food industry needs

The parameters for Class 1 water are very stringent, including:

• Extremely low heavy metal content
• Almost zero hazardous chemical compounds
• Free from pathogens

To achieve this level, recycled water must undergo advanced technologies such as ultrafiltration, reverse osmosis, activated carbon, and multi-stage disinfection systems.

Hygiene and Sanitation vs Class 1 Water: Which Is Appropriate?

The selection of standards must always be based on the intended use:

• If the water is only used for building utilities and is not consumed, then hygiene and sanitation standards are sufficient, safe, and cost-efficient.
• If the recycled water is to be used as raw drinking water, for sensitive industrial processes, or discharged into environmentally protected areas, then Class 1 water quality standards are mandatory.
   

Applying standards that are too low poses health risks, while applying overly high standards for simple uses leads to unnecessary investment and energy waste.

The Importance of Standard Alignment in Recycled Water Systems

Errors in determining the appropriate quality standard can result in:

• System overdesign (high costs, complex operation)
• System underdesign (health risks, regulatory non-compliance)
• Incompatibility with environmental permitting requirements

Therefore, planning a recycled water system must begin with an analysis of human exposure risks, intended use, and applicable regulatory obligations.

Recycled water quality standards cannot be uniform for all applications.

• Hygiene and sanitation standards are suitable for non-consumptive uses such as toilets, gardens, and building utilities.
• Class 1 water quality standards are required if recycled water will serve as a drinking water source or for processes that demand very high quality.

By understanding the differences between these two standards, building managers, industries, and water system planners can develop recycled water installations that are safe, efficient, regulation-compliant, and sustainable.