Keeping waste pipe clear/clean

The waste pipes from my shower and bath to the soil stack, 40mm plastic ones, have runs of approx 2-3 metres. The Shower tray is set on a raised platform of approx 15-20cm. From the shower/bath to the soil stack the pipes rest on the floorboards completely horizontally, with a drop just before they join it. The pipes are hidden underneath/behind floor standing cabinets. All was installed around 3 years ago. I put a (literally) back-of-an-envelope diagram here: http://tinypic.com/r/2ekhj5j/7
With 2 long haired children taking a daily bath, and two (one long haired) adults taking daily showers, the bathroom is well used, and occasionally the shower (never the bath) seem to drain a little slower than usual. I then take the plunger out and in a few seconds retrieve the ball of hair that seem to somehow escape from the trap at the shower waste. No big deal really - only a couple of time a year.
What I did notice though is the unpleasant residue that seem to accumulate in the horizontal part of the pipes, and I am a little concerned that it will eventually cause problems.
Any suggestion as to how to give it the once-over? Pouring a half bucket of diluted Bleach down the bath and shower drains and leave it to rest for a couple of hours perhaps? What is rally important is that it would not be risky, as the access to the pipes (in case of damaging them) is all but impossible without having to rip the cabinets off the wall first.
Many thanks in advance.
J.
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do any of the long haired children own a pet hamster...... the type that loved scurrying through tubes :)
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writes

Any use?
<http://www.google.co.uk/search?client=firefox-a&rls=org.mozilla%3Aen-GB % 3Aofficial&channel=s&hl=en&source=hp&biw80&bih5&q=sink+filter&btnGGoogle+Search#hl=en&ds=pr&xhr=t&q=sink+hair+filter&cp&pf=p&sclient=psy &client=firefox-a&hs=jtY&rls=org.mozilla:en-GB%3Aofficial&channel=s&biw=1 280&bih5&tbs=shop:1&aq=f&aqi=&aql=&oq=sink+hair+filter&pbx=1&fp396d 73eec8aec1>
--
Ian

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Caustic will eat the grease that always accumulates. Conc sulphuric acid will eat organics like hair. Never the 2 shall meet of course, and they're 2 of the riskiest chemicals available for diy. Bleach wont do much.
NT
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I read an interesting article on biofilms recently;
http://www.sciencedaily.com/releases/2011/01/110107101900.htm
this would tend to suggest that the only way of effectively getting the gunk to move is mechanical. Rob
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