Rebecca and her husband Jamie paid $360,000 for the character home in 2010, after searching for a year in Canberra, uninspired by ex-govie homes with a $500,000 price tag.

Empty, unloved and overlooked by other home buyers, the rambling pile with a 1920s brick extension sealed the Duncans' decision to leave Canberra and commute.

Commuters, new shops and homes are presenting Yass with challenges similar to Gungahlin's a decade ago.

The Duncans home, a former boarding house for bank clerks and teachers, was in such a bad state it overwhelmed them as they pondered where to begin the restoration.

For three shivering winters as daughters Matilda, 3, and Elsie, 1, arrived, they used an outdoor bathroom before building one inside.

''When I look out my back door, there's a great big garden for my children to play in,'' Mrs Duncan said. ''The community is fantastic, the doctors and pharmacist are excellent.

''The hospital is another thing, because they transfer most cases to Canberra, so that's a drama.''

Yass Valley's population rose by 10 per cent from 14,114 in 2007 to 15,516 in 2011 and the council's general manager David Rowe says it's at the crossroads.

''If you look at our commercial centre, it is still struggling because of Canberra, even though population has increased,'' he said. ''Everything is so competitive in the retail market these days. It is nothing for people to travel to Canberra to shop at the malls. And you are competing with online as well.''

Yass Chamber of Commerce secretary Ian McClung said promotions were stepped up to get people to shop in Yass rather than Canberra. ''People [from Canberra] are definitely engaging with the local community. It's a slower pace here, you are likely to see someone in the street you know.''

When an Aldi supermarket opened down the road, Mr Duncan secured a deputy manager's role.

Yass builder Shane Doggett says half his business comes from Canberrans, many looking to sell up and put savings from a more affordable home into their superannuation. ''It still has that old town feel to it, where you can park your car in the main street, or around the football oval,'' he said.

Mr Rowe said the town's discoloured water was unlikely to be caused by increased development, or the expanded dam that raised storage capacity from 800 megalitres to 2300 megalitres. Investigations were under way into why water left the treatment plant crystal clear, but picked up iron and manganese somewhere, which discoloured it.

Foremost on Mrs Duncan's mind when she travels on the Barton Highway each morning to her public service job in Canberra is seeing her little girls, named after their grandmothers, at the end of the day.

''You can't help it,'' she said.