Dear PoPville – Identifying Reasons for a Drop in Water Pressure?

Photo by PoPville flickr user jamataya

Dear PoPville,

Sorry if this is completely redundant, but I’ve noticed a significant drop in my water pressure lately, which wasn’t anything to write home about in the first place. I sincerely do not believe there are any leaks in my home. I know, I know. That’s naïve. But I’m a little paranoid about these things, so I watch religiously for leaks through the plaster. I’m sure there’s all kinds of sediment and crud built-up in my pipes (100+ year rowhouse) – the question is, what can I do about that without damaging the pipes? Digging up the finished basement or going through the plaster walls are not the answers I’m looking for……please tell me there’s another way!

18 Comment

  • The hot water pressure dropped in our shower a couple of months ago. I just accepted it as the new reality and moved on. I noticed a couple of days ago a partially closed shut off valve near our hot water heater, I must have nudged it by accident once. Opened it back up and we were back to normal.

    Check your valves.

  • Have you asked your neighbors if they’ve noticed the same thing? If they have then the cause is probably outside your house, so a call to DC Water would then be the next step.

  • Some days are diamonds and some days are coal. Our house has the same issue but very infrequently.

    I always assumed it was a neighborhood issue among the old houses.

    No leaks here either and I suffer from the same “ir-rational leak fear” you mentioned.

  • The same thing happened to me recently–but only with my kitchen sink. And because I had the same fears that something could be very wrong in the main pipes, I had a plumber do preliminary testing with a “snake” to be sure. He found nothing wrong and suggested that it could simply be a clogged faucet. I had a friend come over who knows how to check it out, and indeed it was the problem. We just don’t know whether now to clean it or just buy a new one.

    • If it’s a clogged faucet, it’s very easy to fix. Unscrew the aerator (mesh-lined part that water flows through last) and remove any buildup, then screw it back on. Takes a minute.

  • If you’re experiencing household water pressure issues, DC Water can help. A few things to consider:

    Is low water pressure affecting both hot and cold water taps?
    If it’s only hot water, you should drain your water heater. Water heater instructions -

    If it’s hot and cold water, are you experiencing low water pressure throughout your entire household?
    If low pressure is only affecting specific faucets or floors in your household, you should contact a plumber to inspect your plumbing. Household plumbing guide -

    If you’re experiencing low water pressure at hot and cold water taps throughout the household, contact DC Water at 202-612-3400. We can schedule an appointment with you and investigate the pressure issue.

    DC Water

  • Definitely check with neighbors. DCWater could be working in the area (on a street you don’t necessarily walk by enough) and that could be the cause.

  • Need much more information:
    – Is this in all water fixtures?
    – On all levels?
    – How is the pressure at your hose bibs, if any?
    – Have your neighbors experienced similar drops at similar times?
    – Any chance someone has adjusted your house’s main valve in the basement?
    – Any chance someone has adjusted the valve at the sidewalk/street? (e.g. your neighbor’s contractor who opened the wrong meter box)
    – What type of water service do you have? Lead, steel, or copper? DC Water can tell you the answer if your home inspection doesn’t say (or if you haven’t had it replaced recently).

    All that aside, your aerators and shower heads could be clogged. Unscrew them and check for sediment. Faucets are easier to check than shower heads. I’d put money on the fact that there is a lot of rust and mineral deposit in there. Throw in a 1.5gpm aerator from the hardware store or internet while you’re at it. Most modern versions have excellent water “feel” while still reducing water consumption significantly. You’d be surprised at the drop in your water bill.

    FYI, if the drop were caused by a leak, you would have a major flood within minutes. A small leak wouldn’t have a noticeable effect on pressure.

    • You guys are great! To answer some of the questions, it’s in all faucets, both hot and cold water taps, all floors, and I checked the aerators. They were fairly clogged, but the problem didn’t go away when I cleaned them. Hose bib pressure has always been bad, but is worse now. No chance of someone turning down the water valves at the street or in the basement – both areas are harder to get into than Fort Knox.

      You guys have made me feel better that it’s most likely not a major leak, and the post from DC Water is really helpful. I’ll be calling soon!

      • I’d try closing and reopening the main valve. If it’s really old and rusty there is a small risk of it sticking shut – but then you’d know it’s time to replace it.

        There is a possibility that some crap is stuck in there, and opening and closing it might flush it out. You could also try leaving a hose bib open when you do this — might help with the flushing.

  • If you have a whole house filter on your main, be sure to change is according to schedule. A clog will impact pressure

  • So, related to the picture rather than the question – does anyone know what DC Water is doing with the water there? It’s right outside my apartment over in NoMa, and they have M St NE blocked off in front of Harris Teeter.

    • I would imagine they’re flushing the lines to maintain service and make sure that if there is an emergency, the hydrants can adequately supply water.

      You should ask DC Water though. I’ve found they’re pretty good about responding and explaining their activities/giving time estimates.

  • Readers and our friendly neighborhood water utility (thatnks DC Water! 🙂 have given you lots of great places to start, so I’m just going to pass on a relatively easy way to identify any leaks using a pressure loss test.

    Get a pressure gauge (about $10 at a Home depot/lowes or plumbing supply store), attache it to a normal hose spigot, and shut off the water to your home. Since the piping in your home is a closed system, the pressure should be static. If it’s moving, water is getting out. You can watch them do it as part of this video ( which is about new homes, but the principle is the same.

    Pressure can vary based on lots of things, but may as well know for sure if there’s a leak someplace that’s not materializing above grade.

    Good luck!

Comments are closed.