I am unsure whether that device will be suitable. It mentions, for example, generating electricity from the flow to a shower. Domestic water systems work with a pressure of about 1.5 bar (maybe more) which is equivalent to a pressure head of about 15 metres. Your water supply only has a head of 0.3 meters.
My guess is that you need a device that works with a much lower water flow speed and consequently a much greater cross-sectional area.
...R