Businesses in this category provide equipment, engineering and services for plants that treat gas, water or both, often for industrial, energy, utility and infrastructure applications. Gas treatment systems can remove moisture, particulates and unwanted compounds from gas streams, condition gas for processing or use, and manage emissions and by-products. Water treatment plants may filter, soften or disinfect water, remove dissolved contaminants, or treat process water and wastewater before reuse or discharge. Typical services include planning and designing treatment processes, supplying and installing pumps, filters, separators, tanks, dosing systems, pipework and monitoring controls, and commissioning plant equipment. Businesses may also inspect, maintain and repair systems, replace consumable components, test water or gas quality, and advise on process performance and compliance.