Is London Tap Water Safe?

Remember my friend Lenny from the post below? The horrible consumer of 5 plastic bottles in a day? (Okay, maybe I exaggerate, but I've seen her grab 3 at least!)
She text-messaged me from London she's been now re-using her plastic water bottle with tap water for 10 days & I'd be Ah, so proud! :)

I am not so sure how safe tap water in London is (apparently there may be swine flu abounding too?) or how safe the plastic bottles in London are?
It truly is an eco moment, don't want it to be at the cost of her health though! So hm, what to say? ;) /in a short text-message?;)/

SOME RESEARCH if you want to READ MORE (still no idea how to put stuff behind a 'cut!'):
Well, About.com & the Mayor of London say it's safe! Londontap.org says it's even better than bottled water!
They do say "80% of our drinking water comes from storage reservoirs connected to the River Thames and the River Lee. The remaining 20% comes from boreholes connected to groundwater stores" but the river water is pre-treated & there's natural purification etc & tests show high quality. They also give some really good facts about bottled water use! (some quite shocking!)
People interviewed by BBC seem mostly a bit sceptical still.. & so do people here (in comments - or could it be people financed by bottled water companies?), mainly with regard to taste. Due to years of marketing or..? (Or does BBC have bottled water sponsors too? hm!)

Here in Slovenia, in our region the water seems quite good! Not sure how it is in elsewhere though! - So, hmm?

Must admit I drank tap water in London on my visit there a few years ago - & am still alive! :) I did mix it with a cheap vitamin-rich powder (admittedly not really 'healthy' but it was yummy!)

Similar tips given in a comment by Golodh, London, UK here:
"- store it in the fridge. The deposit (if any) will sink to the bottom, and you taste less when the water is cold (compare e.g. with beer)." - might be doable in a hostel with a kitchen & fridges
"- drink lemonade. Find a brand of cheap squash you like and top it off with chilled bottled water. It will increase your sugar intake, but at least you'll be able to drink it." - doable, real organic lemon would probably be better though - how does lemon juice affect plastic or metal bottles though? I'm still partial to glass myself!
"- filter with active carbon" to remove the taste (?) - hostels could have these available (hopefully with recyclable/refillable filters!)
Good stuff like magnesium can be filtered out too, so only filter when really necessary!
(Well, if you're Coca Cola you can also spend 7 million pounds on marketing it then! Apparently it was even on CNN a few years ago, not sure if Dasani 'purified tap' water is still sold in UK?)

As for the plastic bottle - glass or maybe metal might be better, 10 days is probably okay but she better stay out of direct sunlight & such?!