SpaceX Falcon 9 - starlink mission on October 5. Video :

Why is the water discharged at T- 01m:30s from the holding tank far away from the launch pad? This was also observed in the scrub which happened a week ago.

Water flow appears to be too far away to be considered Sound Suppression System which pumps water near engine nozzle seconds before liftoff .

Happy end to Scrubtober!!

  • $\begingroup$ If the water should not only suppress the sound but also protect the launch pad from the heat of the rocket engine exhaust, some time and water is needed to wet all structures. $\endgroup$
    – Uwe
    Commented Oct 6, 2020 at 18:01
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    $\begingroup$ @uwe I think he means, look at the water tower on the right, and it seems to be venting water from up high... Not the Niagara system itself. $\endgroup$
    – geoffc
    Commented Oct 6, 2020 at 18:28
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    $\begingroup$ IIRC, they top it off by letting it overflow & then just turning off the valve $\endgroup$ Commented Oct 6, 2020 at 19:23

1 Answer 1


This is a post from Reddit user divjainbt who I think will answer your question. He says :

The pumps to fill that tower start few minutes before launch to fill it to the brim for use during launch. Some times the tank fills up all the way earlier than expected due to good water pressure etc. So they vent out excess water rather than shutting down the pumps as pumps need to be active during lift off.

Keeping the water filled to brim and keeping pumps active during liftoff ensures a good water pressure at outlets.

The link is here: https://www.reddit.com/r/SpaceXLounge/comments/jdjvgp/why_did_spacex_pump_water_out_from_the_top_of_the/

I also recommend checking out the other comments on the page to deepen your understanding of this action.

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    $\begingroup$ What I heard is the overflow is not only normal but also planned for as they use the overflow as a "fill gauge". Rather than the complication of installing and maintaining fill sensors it was seen as easier to simply fill until they see water coming out of the top. They don't shut it off at that point they keep the water pumping and overflowing to give a little more oomph when it releases close to T-0. However I don't have a confirming source for this so I can't say the RGOR (random guy on Reddit) is not correct. $\endgroup$ Commented May 22 at 17:22
  • $\begingroup$ I searched the whole internet for this answer $\endgroup$ Commented May 23 at 1:51
  • $\begingroup$ with the help of a modified google search engine to refine results furthur $\endgroup$ Commented May 23 at 1:52
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    $\begingroup$ "I searched the whole internet for this answer" this made my day. I have to admit I only searched half the Internet, so you are to be commended. But seriously not all information makes it into the Google web crawlers, there are lots of different sources of information but it's not always online in searchable documents. And lots of information is not publicly available. Not necessarily being hidden, but unless employees or company spokespeople give details about something it can remain unknowable. And most employees don't talk much publicly, nothing to gain, a lot to lose. $\endgroup$ Commented May 24 at 9:43

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