{HEAD ~ a pair} of {TAIL ~ liquid containers} at substantially the same level including a water container and a detergent container 
of
{ HEAD ~ a pair } of { TAIL ~ liquid containers } at substantially the same level including a water container and a detergent container
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH