aqueduct

cascading

channel

conduit

current

deluge

ditch

downspout

drain

flooding

gurgling

gushing

gutter

heavy

hit

inlet

outlet

overflow

pipe

piping

pouring

raging

rain

roar

runoff

rush

sea

sewage

sewer

smash

spilling

splash

splat

storm

subterranean

surge

surging

swirling

system

tempestuous

torrent

trench

tumultuous

tunnel

turbulent

underground

urban

water

waves

well

gurgle

gush

pour

rage

spill

swirl

wave