one concern when holding that much water is your estrogen levels are probably elevated which could lead to other issues if you dont do something about it. when taking test cyp and you experience water retention i would recommend taking either arimidex to control the conversion of the test to estrogen or nolvadex. .5mg arimidex every other day should suffice.
although the water retention by itself is not much of an issue its the other things that may be occurring alongside the water retention that you need to worry about. make sure you dont have any gyno symptoms like itchy, sore nipples, a small lump forming under the nipple.
excessive estrogen can also cause you to gain fat when on cycle.