ひざに水がたまっているようです。

knee; lap; knee and thigh (while sitting)

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

water (esp. cool, fresh water, e.g. drinking water); fluid (esp. in an animal tissue); liquid; flood; floodwaters; water offered to wrestlers just prior to a bout; break granted to wrestlers engaged in a prolonged bout

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to bear (often adds emphasis); to endure

appearing ...; looking ...; way to ...; method of ...ing; form; style; design; like; similar to; thing (thought or spoken)

be; is