In a liquid treating equipment to maintain a small amount of liquid to a desired liquid level with constantly supplying an additional liquid into a small capacity vessel, a storage vessel 13 to store the small amount of liquid, an injection tube 16 to inject the small amount of liquid into the storage vessel 16, liquid supplying apparatus 23–25 to supply the small amount of liquid into the storage vessel through the injection tube, a flow path 15 of which one end is joined with the storage vessel, a discharge vessel 14, joined with the storage vessel 13 via the flow path, having a larger surface area than that of the storage vessel, a discharge tube 17 of which the discharging inlet is positioned at the same level position as a desired liquid level of the small amount of liquid in the storage vessel and liquid discharging apparatus 27–29 to discharge the liquid from the discharge vessel through the discharge tube are provided. Even though the liquid level in the discharge vessel is largely fluctuated, the liquid level in the storage vessel is almost never done.