Protecting East Hampshire’s underground natural reservoirs and water purifying plants - chalk aquifers - is a Liberal Democrat priority.

The party’s East Hampshire parliamentary candidate, Dominic Martin, and its Alton Whitedown district councillor, Ginny Boxall, aim to conserve them, and chalk streams.

Chalk aquifers store rain and filter it through tiny fissures and fractures before gradually releasing clear and mineral-rich water into chalk streams such as the rivers Itchen, Meon and Wey, supplying much of East Hampshire’s drinking water.

The Lib Dems called them “critical public infrastructure” and their South Cambridgeshire MP Pippa Heylings is expected to introduce a Ten Minute Rule Bill demanding the government ask UNESCO for Natural World Heritage Site recognition for chalk streams.

Cllr Boxall helped secure stronger chalk stream protection in the council’s emerging Local Plan and revived the Northern Wey Community Trust, which meets on March 17.

But she warned of a “serious threat” to East Hampshire’s water security: “Due to climate change and increased housing targets for East Hampshire District Council, we face water shortages if the floodplains surrounding our chalk aquifers - which deliver our water - are concreted over.

“I have been flagging our concerns to the East Hampshire planning team and have highlighted the urgent need to protect the Wey catchment area and to protect and enhance all our chalk streams and rivers.

“There is concern from local experts that the chalk aquifers that supply our water could fail through a mixture of no longer being able to recharge - as hard surfaces prevent water penetrating the aquifers - increased run-off which risks sewer flooding, and drier summers. It’s a perfect storm that is brewing.”

Dominic Martin added: “We need stronger safeguards, tougher action on pollution and water companies held properly to account. Planning decisions must recognise the limits of our aquifers, and investment must prioritise reducing leakage and improving water efficiency before expanding supply.”