Income at WaterAid has jumped by 10 per cent after the charity posted an increase of more than 20 per cent in grant funding.
In its accounts for the year to 31 March 2019, the charity’s income hit £91.4m, compared with £83.4m the previous year.
Spending also rose slightly, from £81.9m to £82.6m, the accounts show.
Income from donations and legacies increased from £52.1m to £53.4m, with legacies doing particularly well, rising by nearly £1.9m.
But it was grant funding that performed particularly well, rising from £23m to £28m in 2018/19.
The charity said in the accounts that the rise in grant funding could be explained by a change in approach outlined by the charity in the 2017/18 accounts.
The 2017/18 accounts said that the charity had restructured its team charged with bringing in funding from institutional sources and had brought in "talented global leadership".
The success of the changes brought large increases in funding from countries and organisations such as the Swedish government, the European Commission and the bank HSBC.
"The UK charity sector has seen a consistent decline in the volume and value of funds raised by the public over the last three years," the report says, but adds that the charity "bucked the trend" by growing its fundraised income.
Marcus Missen, the charity’s director of communications and fundraising, was among those who warned that charities needed to shift strategies on fundraising.
In an article published on the Third Sector website last year, Missen said that the existing fundraising model was "broken".
"We want ’partners in the mission’, not just ‘funders of the mission’," Missen wrote.
"So we look to collaborate and co-create with individuals and businesses, focusing on building shared value. In other words, we deliver mission and provide value to our partner’s objectives."