She'll feed it to her two youngest children - two-year-old Zahara and 14-month-old Gebriel.
Both were found to be moderately malnourished and suffering from diarrhoea on a recent visit to the health centre.
Zahara and Gebriel are just two of thousands of children under five in Eritrea who are suffering from malnutrition as a result of repeated droughts.
Their treatment is part of the DFID-funded CAFOD Emergency Nutrition Project, which is providing 10,000 moderately malnourished children and pregnant and lactating mothers in Eritrea with a supplementary food ration to prevent severe malnutrition.
Zahara and Gebriel have gained weight and the family is benefiting from the health education sessions Tsega attends as another part of the programme.
"During the health education sessions, I learned that the water I had been using for drinking is not clean," explains Tsega.
"So I started to follow the recommendations of the health educator and boil the water before drinking.
"Since I started to give boiled water to the children, their diarrhoea has disappeared."
NB: Names have been changed to protect identities
Key facts and stats:
The UN estimates that over 15 million people are in need of humanitarian assistance across East Africa as a result of one of the worst droughts to hit the region in over a decade.
The CAFOD Emergency Nutrition project aims to reduce the incidence of malnutrition in the Anseba, Debub, Northern Red Sea and Gash Barka zones of Eritrea, which have been badly affected. Around 6,700 women and children have benefited from the project since it began in August 2009.
Under-nourishment is a continuing problem for Eritrea. According to the UN's Food and Agriculture Organisation (FAO), an estimated 66% of the population is underfed.
DFID's engagement in Eritrea is limited to humanitarian assistance. Department officials will continue to monitor the situation in Eritrea closely, alongside relief partners, like CAFOD.