Cold open — the break. It's quarter to eight. Somebody upstairs is in the shower, and the kitchen tap just went weak. And in the living room, the show everyone's watching has stopped to think about it. Those two things have more in common than you'd expect. They're both pipes. They're both shared with the neighbors. And they can both get worse at the exact moment everybody wants them. Let's take the house apart and look.

The house — two sets of pipes. Every house has a water main. A pipe comes in from the street, goes through a meter on the wall, past a shutoff valve, into a manifold, and from there it branches off to every tap in the place. Your internet does almost exactly the same thing. A line comes in from the street. It goes into a box on the wall. From there, into a router, and the router hands it out to every device in the house. Some over cables. Most over the air. Same layout. Different stuff in the pipe. So let's follow it backwards, from the tap to the reservoir.

Where the pipe starts. Your water comes from a reservoir and a treatment plant. Your internet comes from data centers. Big, cold, windowless buildings full of computers, holding the videos and the email and the websites. And the pipes that connect them are mostly glass. People picture the internet in the sky, beamed from satellites. Some of it is. But nearly all of the traffic between continents runs through cables lying on the floor of the ocean. Just over six hundred of them. For most of the way across, each one is about as wide as a garden hose. When you watch something made on the other side of the world, it very likely came to you along the bottom of the sea.

The water tower down the road. Here's a detail most people never hear about. Your town doesn't pump every glass of water all the way from the reservoir. There's a water tower up the hill, holding a supply close by. The big video services do the same thing. They put copies of their popular shows in buildings near you. Often inside your internet provider's own building, on machines the video company hands them for free. It saves everybody the long haul. So the show you're watching tonight probably didn't cross an ocean. It came from a few miles away, out of somebody's water tower. The trade has a name: a content delivery network.

What's actually in the pipe. Inside those cables, and probably in the street outside your house, the pipe is a strand of glass thinner than a hair. And what flows through it isn't water. It's light. Tiny flashes, on and off, billions of times a second. On is a one. Off is a zero. Light in glass travels at about two-thirds of its top speed. Roughly two hundred thousand kilometres every second. That sounds instant. It isn't quite. From Seattle to New York, the light needs about twenty thousandths of a second, one way, and that's in a perfectly straight line. Real cables don't run straight. Nobody can make that faster. That's physics, not your provider.

Pipe size versus distance. Which brings us to the most misunderstood thing about internet speed. When you buy a faster plan, you're buying a wider pipe. More water per second. That's called bandwidth. Great for filling a bathtub, or downloading a big file. But a wider pipe doesn't make the first drop arrive any sooner. How long that first drop takes is called latency, and it's mostly about distance. A fire hose to the other side of the world still takes the same time to start dripping as a straw. That's why a video call can stutter on a very fast plan. The call doesn't need a bathtub. It needs every little drop on time.

Buckets, not a stream. Here's where the water story needs one correction. Water is one continuous stream. Data isn't. Everything you send or receive gets chopped into small pieces called packets. On a normal home network, each one carries at most about fifteen hundred bytes. Think buckets, not a stream. Every bucket has an address label on it, so it can find its own way, and the buckets get put back in order at the other end. A movie is millions of buckets. We'll come back to what happens when one gets spilled. That's its own episode.

The meter on the wall. Back at the house. Where the water main has its meter, your internet has a box on the wall. If your line is fiber, that box is called an O-N-T, and its whole job is translation. Light in, electrical signal out. If your line is the cable TV kind, made of copper, the box is a modem doing the same job over the same wire that carries the TV. After the box comes the router. That's your manifold. It takes one supply and shares it between every tap in the house, and it keeps track of which bucket belongs to which room.

The taps. And then the taps. A network cable is a proper pipe. The ordinary kind in most walls carries a full gigabit, up to a hundred metres. Wi-Fi is more like a sprinkler. It's convenient, it reaches everywhere, and it loses pressure with every wall, every floor and every refrigerator it has to get through. And everybody in the room is sharing the same spray. So you can pay for a big pipe at the street and still be drinking through a sprinkler in the back bedroom. A lot of the time, the street isn't the narrow part. The last ten metres are.

The break — everybody showers at seven. Now the part that ruins your evening. That line from the street isn't really yours. Out on the pole, or in a box at the end of the road, your house shares a connection with your neighbors. With fiber, one strand from the provider is split between as many as thirty-two or sixty-four homes. With cable, the street shares the same wire. The providers size that shared pipe on a bet: that not everybody will open their taps at the same time. It's called oversubscription, and most of the day it's a pretty safe bet. And then it's seven forty-two, and everybody on the street sits down to stream something at once. Every shower in the neighborhood is running. Your plan didn't change. Your neighbors' habits did. That's the shit nobody puts on the speed sticker. To be fair to the providers: when the government measured this, most people saw only a small dip at peak time. When yours is more than small, this is usually why.

The fix — find the narrow part. So before you blame anybody, find the narrow part. It takes ten minutes. Run a speed test with a cable plugged straight into the router. Then run it on Wi-Fi in the room where it's bad. If the cable is fast and the Wi-Fi isn't, it's the sprinkler. Move the router, or run a cable to the thing that matters. If both are slow, test again in the middle of the afternoon. Fine at three and slow at eight means it's the street, not your house. And that's a phone call to your provider, with numbers in hand.

The button. The internet is a lot of very fast glass, a box on your wall, and a quiet bet that your neighbors won't all shower at once. Most nights, the bet pays off.

Cold open. Quarter to eight. The shower's running, the kitchen tap's gone weak, and the show just froze. Same problem, twice. Shared pipes.

Pipe size versus distance. A faster plan is a wider pipe. More per second. It doesn't make the first drop arrive any sooner. That's distance, and nobody can sell you less of it.

The break. And your line from the street is shared with the whole road. Providers bet everyone won't open their taps at once. Some nights, at seven forty-two, everyone does.

The fix. Test on a cable, then on Wi-Fi. Then at three, and at eight. Fine at three, slow at eight: it's the street, not your house.

The button. How the internet actually gets into your house, in Episode 1.