The industrial action at Northern Ireland Water concerns proposed changes to employees' pensions.
The pension system is being changed right across the public sector. The Government says that with increased life expectancy the system is becoming unaffordable. Therefore public sector employees are being told they will have to work longer and pay in more.
In the current final salary pension scheme, staff at NIW pay in 1-3% while the company pays in 26%.
Under the proposed changes staff would still receive about 20% of their salary in employer contributions. NI Water chief executive Sara Venning said: "We run two schemes with two contribution rates.
"Staff are either paying 1.5% or 3.5% of their salary into their pension, and the company then is matching with approximately 26% of salary into the pension."
She said the changes would mean an average of 4.5% and 5% staff pay-in, with the company paying in around 20%.
Ms Venning confirmed her own pension would be affected by the changes. "Everybody at NI Water would be affected equally," she added.
Ms Venning joined NI Water in April 2010 as director of customer service delivery with responsibility for water treatment and distribution, wastewater collection and treatment, together with all aspects of service to customers.
According to NI Water's latest annual report, she earns between £130,000 and £135,000 a year, plus pension benefits of £51,000.
It brings her total financial package to £185,000 to £190,000.
Her salary has increased from 2012/13, when it was £115,000, to £120,000. The other two executive directors are Ronan Larkin, director of finance and regulation, and George Butler, director of asset management. Their salaries are £105,000 to £110,000, with pension benefits of £27,000 and £26,000 respectively.
Also sitting on the executive committee is Alec McQuillan, the acting director of customer service delivery, and Bill Gowdy, director of engineering and procurement. Both earn £90,000 to £95,000.
The sixth senior official is Mark Ellesmere, general counsel and company secretary, who earns £100,000 to £105,000.