At a time when most water companies are being criticised for putting profit and shareholders before customers and offering a substandard service, one appears to be bucking the trend.

Welsh Water, owned by the not-for-profit company Glas Cymru, is unveiling investment of £1bn over the next three years on infrastructure projects in Wales, Herefordshire and Deeside.

The company is upgrading its treatment works – rebuilding 22 of them – ploughing more money into renewable energy projects and maintaining its networks of water mains and sewers. And at the same time, the company reports that household bills are falling in real terms.

Chris Jones, the company's finance director, said the not-for-profit model meant the company did not have to chase short-term gains. "We can take a long-term perspective. All money we make gets invested back into the business. That's why we're investing more even in difficult times."

The company, which has 2,000 employees, says its investment means jobs for a further 1,500 people in the construction industry – accounting for around a tenth of those working in the building sector in Wales.

Welsh Water (Dŵr Cymru in Welsh) is also proud that, unlike some of its English counterparts, it has not had to impose a hosepipe ban for 23 years.

Jones said that was not just because it did rain a lot in Wales – the last two springs have been relatively dry – but because leakage was at an all-time low.

Introducing the not-for-profit water company model has been discussed in Scotland and visitors from as far afield as Japan and Australia have visited the company, which reveals its results on Thursday.

One project not on the drawing board is finding a way of selling water to drier places of the UK such as the south-east of England.

Jones said that would necessitate a major engineering scheme, including building a new reservoir, as the company does not store a huge amount of excess water, and finding a cost-effective way to move it east. He said: "It's technically possible, it's worth considering as an option but it's not a cheap option, it would be expensive to do."

Since 2001, Welsh Water has been owned, financed and managed by Glas Cymru. Unique in the water and sewerage sector, Glas Cymru is a company limited by guarantee and as such has no shareholders – it is run by a board, which has a majority of independent non-executive directors, and its members. These members total around 70 individuals who are unpaid and whose duty is to promote the good running of the company in the best interests of its customers.