Two remarkable sisters are about to complete the equivalent of a cross-Channel marathon swim, raising more than £23,000 for Jewish and non-Jewish charities in the process.

Talya and Dani Jacobson have been taking to the water at their local baths most days over the past few months to swim 1,408 lengths of the 25m indoor pool, the equivalent of the 22-mile width of the English Channel.

It was 12-year-old Dani, a pupil at North London Collegiate School, who had the idea as a way of marking her batmitzvah, which takes place at Borehamwood and Elstree Synagogue next month. Wanting to express her gratitude for all she has by giving to others less fortunate, she also had a more personal reason. Her goal was to raise money for groups which had supported older sister, Talya, 13, who has learning difficulties as a result of contracting meningitis as a baby.

Talya, who herself raised £15,000 through a sponsored triathlon when she celebrated her batmitzvah 18 months ago, decided that she would join in her sister’s challenge, which they called “Sister Strength”. Together, they wrote to friends and family to solicit sponsorship. Their success will benefit several charities including Lonsdale School in Stevenage, where Talya is a pupil and Kisharon, but the bulk of the cash will go to Norwood, which provided the family with a lifeline during Talya’s early years.

The sisters have been supported throughout their swims by their parents, Beverly and Alan, and their younger siblings, nine-year-old Harry and six-year-old Gemma. “It was quite something to witness the girls’ camaraderie in the water,” their mother  told the JC.