the Hutt Valley Electric Power Board and installed in Johnsonville by Norman Heath & Co. The board was active in the 1912-1922 period when gas lighting and drainage were installed and streets kerbed and channeled. In 1912 a water reservoir was built for water supplied from Ohariu Valley, and a new reservoir built in 1922. Drainage installed in 1912 was to a septic tank in Ngauranga Gorge. The septic tank lasted to 1953; when Johnsonville amalgamated with the Wellington City Council in April and the council completed a main sewer to the area. Surrounding areas also joined Wellington; like Raroa, which had been in the Hutt County Council. The Town Board area was extended to the Hawtrey Estate north of Ironside Road from 1 April 1932, and the board installed some standpipes to fill water buckets. The population grew from 143 in 1874 to 206 in 1878 and 438 (in 83 dwellings) in 1897. The population almost doubled between 1901 (502) and 1911, and was just over 3000 by 1951. In 1976 it was 9230; a 37% increase 1956-66 and 106% increase 1966–76. Wellington suburb The town grew rapidly from 1938 with state houses built on the former Native Reserve between Broderick Road and Fraser Avenue; the first was built in Bould Street. From 1938 to 1956, 329 state houses were built. In the 1960s, the first shopping mall in the Wellington region was built in Johnsonville. Demographics Johnsonville, comprising the statistical areas of Johnsonville West, Johnsonville North, Johnsonville Central and Johnsonville South, covers . It had an estimated population of as of with a population density of people per km2. Johnsonville had a population of 11,106 at the 2018 New Zealand census, an increase of 870 people (8.5%) since the 2013 census, and an increase of 1,866 people (20.2%) since the 2006 census. There were 3,942 households. There were 5,394 males and 5,712 females, giving a sex ratio of 0.94 males per female, with 2,211 people (19.9%) aged under 15 years, 2,202 (19.8%) aged 15 to 29, 5,349 (48.2%) aged 30 to 64, and 1,350 (12.2%) aged 65 or older. Ethnicities were 61.2% European/Pākehā, 9.8% Māori, 5.9% Pacific peoples, 30.3% Asian, and 3.8% other ethnicities (totals add to more than 100% since people could identify with multiple ethnicities). The proportion of people born overseas was 36.7%, compared with 27.1% nationally. Although some people objected to giving their religion, 43.9%