noun
water filter; water purifier
A device or system for filtering and purifying water, commonly used in homes and offices.
新しい浄水器をキッチンに取り付けた。
I installed a new water filter in the kitchen.
この浄水器は水道水をきれいにしてくれる。
This water purifier makes tap water clean.
浄水場 is a water purification plant (large-scale facility), whereas 浄水器 is a smaller household appliance.
Compound of 浄水 (purified water) + 器 (device, instrument). The exact historical derivation is uncertain, but the kanji composition directly reflects the meaning.