makeupwater

Makeup water is water added to a closed or semi-closed industrial system to compensate for losses due to evaporation, leakage, purge, and bleed-off. It is commonly used in loops such as steam boiler systems and cooling-water circuits to maintain system inventory and pressure and to prevent dry-out.

In practice, makeup water is typically treated before entering the system to minimize adverse effects from impurities. In boiler systems, makeup water becomes feedwater after pretreatment and deaeration and must be low in dissolved solids, hardness, silica, and oxygen to reduce scaling and corrosion. Common treatments include pretreatment, softening, reverse osmosis or deionization, deaeration, and chemical dosing such as oxygen scavengers, carbonate alkalinity control, and anti-scalants. The use of condensate recovery and bleed-off management reduces the amount of makeup water required.

Quality requirements depend on the system. High-pressure boilers require very low concentrations of dissolved solids, while cooling towers may tolerate higher levels but aim to minimize corrosion and biofouling.

Sources of makeup water include municipal or well water, surface water, or treated process water. In seawater installations, makeup water may come from desalination.

Monitoring and control involve conductivity or resistivity measurements, total dissolved solids, silica, chlorides, pH, dissolved oxygen, and periodic chemical analyses to ensure compliance with design limits.

Environmental and economic considerations favor maximizing water reuse and efficient treatment, reducing blowdown and energy use while ensuring system integrity.