Waters was the Greens' Brisbane Central Candidate in the 2006 Queensland state election running against then Premier Peter Beattie, securing almost 5,000 votes. Waters was the lead Senate candidate for the Greens in Queensland at the 2007 federal election. The party received 7.3 percent of the statewide vote, but this was not enough to secure her election. Waters again stood for office at the 2009 Queensland state election, running for the seat of Mount Coot-tha. The seat was held by the sitting Treasurer of Queensland, Andrew Fraser of the Labor Party. She polled 23.1 percent on first preferences, with Ronan Lee the only Greens candidate with a higher percentage. Waters was again placed first on the Greens' senate ticket at the 2010 federal election. She was elected with 12.8 per cent of the vote, an increase of 5.4 percentage points. In May 2015, Waters was elected to the Greens' "leadership triumvirate". She was made a "co-deputy leader" alongside Scott Ludlam, with Richard Di Natale replacing Christine Milne as the party leader. Waters was re-elected to the senate at the 2016 double-dissolution election, winning a three-year term with 6.9 percent of the vote.
Resignation
Waters was forced to resign from the Senate on 18 July 2017, after it was uncovered that she was entitled to dual Canadian-Australian citizenship, thereby making her ineligible to be elected under section 44 of the Australian Constitution. Her resignation came four days after her fellow Greens co-deputy leader Scott Ludlam had resigned from the Senate over dual citizenship, which prompted several other MPs and Senators to clarify their citizenship status. Waters had been born to Australian parents in Canada, and returned with them to Australia as a baby. She stated that she had previously believed she was solely an Australian citizen, and if she had wished to gain Canadian citizenship she would have needed to take active steps before age 21—but now discovered she had in fact held dual citizenship since birth. Her seat was filled by a recount, which saw former Australian Democrats leader Andrew Bartlett, who held the second position after Waters on the Greens' 2016 Senate ticket in Queensland, return to the Senate. On 8 August 2017, Waters announced that she had renounced her Canadian citizenship and declared her intent to stand for Greens preselection and return to parliament at the next federal election. The High Court handed down its decision on 27 October 2017 and ruled that Waters was invalidly elected.
Return
On 3 April 2018, Waters was announced as the Queensland Greens lead Senate candidate for the next federal election, with Andrew Bartlett instead opting to contest the lower house seat of Brisbane. On 16 June 2018, Bartlett announced that he would resign from the senate at the end of August, and Waters was preselected to fill the resulting casual vacancy ahead of the election. On 6 September 2018, the Parliament of Queensland re-appointed Waters to the Senate. The Greens party room returned Waters to the co-deputy leadership on 4 December 2018. Waters was re-elected as a Senator for Queensland at the 2019 federal election, where she received 9.9% of the state's vote, as well as a 3.12% swing in her favour.
Coronavirus commentary
During the COVID-19 crisis in March 2020, Waters earned criticism for sharing a social media post that criticised Prime Minister Scott Morrison, that described the virus as "Scomo’s revenge" and calling him an "arsehole".
Personal life
Waters was married to journalist Brendan O'Malley and they have one child together born in 2009. Waters and O'Malley separated in 2013 and share care of their daughter. Waters has another child born in 2016 to former partner Jeremy Gates.
