i realised i shouldve explained my circuit a bit more, so here goes:
the majority of the circuit is based around a monostable, because i am going to have two 2 infrared inputs, an on/off one depending on whether hands are there or not, and a timed on, so the water runs for a set amount of time (reason for switch on capacitors to change time length). This circuit is currently just for one tap, and i would have to make another one for the other tap, i have made sure the solenoid runs off 6v in real life, and the op amps i am using are LM324s. i think that make things a bit more clear to you.