Exclusive: Company relies on obsolete tech and there are troubling security gaps, Guardian investigation suggests

• Thames Water supply ‘on knife-edge’
• Floods, explosions, asbestos: Thames faces problems on all fronts

“The software we use is older than me, and some of the hardware is older than my dad,” says Siddharth*. He is one of a team fighting a daily battle to sustain ancient IT infrastructure at Thames Water.

Sometimes the defences are breached. Thames, the UK’s largest water and waste treatment company, is on a “knife-edge” according to sources, with its resilience in doubt because it depends on an array of creaking – often Victorian – infrastructure.