what is the difference between injections and leakages?
Injection into economy include investment, government purchases and exports while leakages include savings, taxes and imports. Government taxes leak out of the circular flow model and then government spending injects them back into the economy. Leakages reduce the flow of income while Injection increase the flow of income.
A leakage means the withdrawal of a part of income (money) from the circular flow of income. For instance, savings and taxes by households, and firms, as well as import payments, are forms of leakage. Injections are the addition of money to the circular flow of income, e.g., investments, government expenditure, export payments.