Reference for Chullin 174:13

אין דם מבטל דם

but where the blood fell into the water each drop became neutralized [as it fell into the water].<span class="x" onmousemove="('comment',' And even if there fell into the water so large a quantity of blood as to give to the whole the appearance of blood, it is unfit for its purpose; for as each drop fell into the water it became neutralized and immediately lost its validity for the purposes of ritual sprinkling, and it cannot regain it even though the whole mixture has the colour of blood.');">⁷</span>

Explore reference for Chullin 174:13. In-depth commentary and analysis from classical Jewish sources.