Probably discard it. Hypochlorite is unstable, and it loses potency. Or, if you’re feeling adventurous, dilute it 1:20000 or so and measure it with a pool tes

Probably discard it. Hypochlorite is unstable, and it loses potency. Or, if you’re feeling adventurous, dilute it 1:20000 or so and measure it with a pool test kit. Also, one of the degradation products is chlorite, which is somewhat nasty. You can find actual research from the swimming pool chemical industry. At higher concentrations (bleach sold for swimming pools is more concentrated), it’s less stable and apparently should ideally be used within 30 days in hot weather. The household stuff ought (good luck!) to be more stable, and you’re probably not storing it in a hot pool equipment room.