You first need to read the sewer easement that burdens your property and benefits the other two properties as to the scope of it and what stated obligations there are as to maintance and upkeep in that its terms control in the absence of state law.If the easement is silent on the subject of repair on the common sewer pipe the laws of California require the owner of any easement to maintain and repair it so as to keep it in good order. Since you and two other property owners share a common sewer pipe for the benefit of all three properties through this sewage line easement, all three of you should be sharing equally in the $2,200 cost of repair.You should first write the other two property owners a letter referencing this with a copy of the $2,200 estimate requesting their equal contribution. If they refuse to contribute, your option is to make the repairs and seek contribution from them in a small claims court action. Keep a copy a copy of all letters sent them.